Shielded electrical cable

ABSTRACT

A shielded electrical cable is disclosed. The cable includes a plurality of conductor sets that extend along the length of the cable and are spaced apart from each other along the width of the cable. Each conductor set includes one or more insulated conductors, and first and second shielding films that are disposed on opposite first and second sides of the cable. The first and second films include cover portions and pinched portions arranged such that, in transverse cross section, the cover portions of the first and second films in combination substantially surround each conductor set, and the pinched portions of the first and second films in combination form pinched portions of the cable on each side of each conductor set. Each conductor set also includes an EMI absorbing layer that is disposed on the first side of the cable, and an adhesive layer that bonds the first shielding film to the second shielding film in the pinched portions of the cable. The plurality of conductor sets includes a first conductor set that includes neighboring first and second insulated conductors and has corresponding first cover portions of the first and second shielding films and corresponding first pinched portions of the first and second shielding films that form a first pinched region of the cable on one side of the first conductor set. The maximum separation between the first cover portions of the first and second shielding films is D. The minimum separation between the first pinched portions of the first and second shielding films is d 1 . d 1 /D is less than 0.25. The minimum separation between the first cover portions of the first and second shielding films in a region between the first and second insulated conductors is d 2 . d 2 /D is greater than 0.33.

TECHNICAL FIELD

This invention generally relates to electrical cables that include oneor more EMI absorbing layers.

BACKGROUND

Electrical cables for transmission of electrical signals are well known.One common type of electrical cable is a coaxial cable. Coaxial cablesgenerally include an electrically conductive wire surrounded by aninsulator. The wire and insulator are surrounded by a shield, and thewire, insulator, and shield are surrounded by a jacket. Another commontype of electrical cable is a shielded electrical cable that includesone or more insulated signal conductors surrounded by a shielding layerformed, for example, by a metal foil.

SUMMARY

Generally, the present invention relates to shielded electrical cables.In one embodiment, a shielded electrical cable includes a plurality ofconductor sets that extend along a length of the cable and are spacedapart from each other along a width of the cable. Each conductor setincludes one or more insulated conductors; and first and secondshielding films that are disposed on opposite first and second sides ofthe cable. The first and second films include cover portions and pinchedportions arranged such that, in transverse cross section, the coverportions of the first and second films in combination substantiallysurround each conductor set, and the pinched portions of the first andsecond films in combination form pinched portions of the cable on eachside of each conductor set. Each conductor set further includes a firstEMI absorbing layer that is disposed on the first side of the cable; anda first adhesive layer that bonds the first shielding film to the secondshielding film in the pinched portions of the cable. The plurality ofthe conductor sets includes a first conductor set that includesneighboring first and second insulated conductors and has correspondingfirst cover portions of the first and second shielding films andcorresponding first pinched portions of the first and second shieldingfilms that form a first pinched region of the cable on one side of thefirst conductor set. The maximum separation between the first coverportions of the first and second shielding films is D. The minimumseparation between the first pinched portions of the first and secondshielding films is d₁. d₁/D is less than 0.25. The minimum separationbetween the first cover portions of the first and second shielding filmsin a region between the first and second insulated conductors is d₂.d₂/D is greater than 0.33. In some cases, d₁/D is less than 0.1. In somecases, the first EMI absorbing layer is disposed between the firstshielding film and the plurality of conductor sets. In some cases, thefirst shielding film is disposed between the first EMI absorbing layerand the plurality of conductor sets. In some cases, the cable furtherincludes a second EMI absorbing layer that is disposed on the secondside of the cable.

In another embodiment, a shielded electrical cable includes a pluralityof conductor sets that extend along a length of the cable and are spacedapart from each other along a width of the cable. Each conductor setincludes one or more insulated conductors; and first and secondshielding films that are disposed on opposite first and second sides ofthe cable. The first and second films include cover portions and pinchedportions that are arranged such that, in transverse cross section, thecover portions of the first and second films in combinationsubstantially surround each conductor set, and the pinched portions ofthe first and second films in combination form pinched portions of thecable on each side of each conductor set. Each conductor set furtherincludes a first EMI absorbing layer that is disposed on the first sideof the cable; and a first adhesive layer that bonds the first shieldingfilm to the second shielding film in the pinched portions of the cable.The plurality of conductor sets includes a first conductor set thatincludes neighboring first and second insulated conductors and hascorresponding first cover portions of the first and second shieldingfilms and corresponding first pinched portions of the first and secondshielding films that form a first pinched cable portion on one side ofthe first conductor set. The maximum separation between the first coverportions of the first and second shielding films is D. The minimumseparation between the first pinched portions of the first and secondshielding films is d₁. d₁/D is less than 0.25. The high frequencyelectrical isolation of the first insulated conductor relative to thesecond insulated conductor is substantially less than the high frequencyelectrical isolation of the first conductor set relative to an adjacentconductor set. In some cases, d₁/D is less than 0.1. In some cases, thehigh frequency isolation of the first insulated conductor relative tothe second conductor is a first far end crosstalk C1 at a specifiedfrequency range of 3-15 GHz and a length of 1 meter, and the highfrequency isolation of the first conductor set relative to the adjacentconductor set is a second far end crosstalk C2 at the specifiedfrequency, and C2 is at least 10 dB lower than C1. In some cases, thecover portions of the first and second shielding films in combinationsubstantially surround each conductor set by encompassing at least 70%of a periphery of each conductor set.

In another embodiment, a shielded electrical cable includes a pluralityof conductor sets that extend along a length of the cable and are spacedapart from each other along a width of the cable. Each conductor setincludes one or more insulated conductors; and first and secondshielding films that include concentric portions, pinched portions, andtransition portions arranged such that, in transverse cross section, theconcentric portions are substantially concentric with one or more endconductors of each conductor set, the pinched portions of the first andsecond shielding films in combination form pinched portions of the cableon two sides of the conductor set, and the transition portions providegradual transitions between the concentric portions and the pinchedportions. Each conductor set also includes a first EMI absorbing layerthat is disposed on the plurality of conductor sets. Each shielding filmincludes a conductive layer. A first one of the transition portions isproximate a first one of the one or more end conductors and has across-sectional area A₁ defined as an area between the conductive layersof the first and second shielding films, the concentric portions, and afirst one of the pinched portions proximate the first end conductor. A₁is less than the cross-sectional area of the first end conductor. Eachshielding film is characterizable in transverse cross section by aradius of curvature that changes across the width of the cable. Theradius of curvature for each of the shielding films is at least 100micrometers across the width of the cable. In some cases, thecross-sectional area A₁ includes as one boundary a boundary of the firstpinched portion. The boundary is defined by the position along the firstpinched portion at which a separation d between the first and secondshielding films is about 1.2 to about 1.5 times a minimum separation d₁between the first and second shielding films at the first pinchedportion. In some cases, the cross-sectional area A₁ includes as oneboundary a line segment having a first endpoint at an inflection pointof the first shielding film. In some cases, the line segment has asecond endpoint at an inflection point of the second shielding film.

In another embodiment, a shielded electrical cable includes a pluralityof conductor sets that extend along a length of the cable and are spacedapart from each other along a width of the cable. Each conductor setincludes one or more insulated conductors; and first and secondshielding films that include concentric portions, pinched portions, andtransition portions arranged such that, in transverse cross section, theconcentric portions are substantially concentric with one or more endconductors of each conductor set, the pinched portions of the first andsecond shielding films in combination form pinched regions of the cableon two sides of the conductor set, and the transition portions providegradual transitions between the concentric portions and the pinchedportions. Each conductor set also includes a first EMI absorbing layerthat is disposed on the plurality of conductor sets. One of the twoshielding films includes a first one of the concentric portions, a firstone of the pinched portions, and a first one of the transition portions.The first transition portion connects the first concentric portion tothe first pinched portion. The first concentric portion has a radius ofcurvature R₁ and the transition portion has a radius of curvature r₁.R₁/r₁ is in a range from 2 to 15.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be more completely understood and appreciated inconsideration of the following detailed description of variousembodiments of the invention in connection with the accompanyingdrawings, in which:

FIG. 1 is a perspective view of an exemplary embodiment of a shieldedelectrical cable;

FIGS. 2 a-2 g are front cross-sectional views of seven exemplaryembodiments of a shielded electrical cable;

FIGS. 3 a-3 d are front cross-sectional views of four other exemplaryembodiments of a shielded electrical cable;

FIGS. 4 a-4 c are front cross-sectional views of three other exemplaryembodiments of a shielded electrical cable;

FIGS. 5 a-5 e and 5 f-5 g are perspective and front cross-sectionalviews, respectively, illustrating an exemplary method of making ashielded electrical cable;

FIGS. 6 a-6 c are front cross-sectional views illustrating a detail ofan exemplary method of making a shielded electrical cable;

FIGS. 7 a-7 b are a front cross-sectional view of another exemplaryembodiment of a shielded electrical cable according to an aspect of thepresent invention and a corresponding detail view, respectively;

FIGS. 8 a-8 b are front cross-sectional views of two other exemplaryembodiments of a shielded electrical cable according to an aspect of thepresent invention;

FIGS. 9 a-9 b are front cross-sectional views of two other exemplaryembodiments of a shielded electrical cable;

FIGS. 10 a-10 c are front cross-sectional views of three other exemplaryembodiments of a shielded electrical cable;

FIGS. 11 a-11 g are front cross-sectional detail views illustratingseven exemplary embodiments of a parallel portion of a shieldedelectrical cable;

FIGS. 12 a-12 b are front cross-sectional detail views of anotherexemplary embodiment of a parallel portion of a shielded electricalcable;

FIG. 13 is a front cross-sectional detail view of another exemplaryembodiment of a shielded electrical cable in a bent configuration;

FIG. 14 is a front cross-sectional detail view of another exemplaryembodiment of a shielded electrical cable;

FIGS. 15 a-15 f are front cross-sectional detail views illustrating sixother exemplary embodiments of a parallel portion of a shieldedelectrical cable;

FIG. 16 a-16 b are front cross-sectional views of two other exemplaryembodiments of a shielded electrical cable;

FIG. 17 is a front cross-sectional view of another exemplary embodimentof a shielded electrical cable;

FIG. 18 is a front cross-sectional view of another exemplary embodimentof a shielded electrical cable;

FIG. 19 is a front cross-sectional view of another exemplary embodimentof a shielded electrical cable;

FIG. 20 a-20 d are front cross-sectional views of four other exemplaryembodiments of a shielded electrical cable;

FIG. 21 is a front cross-sectional view of another exemplary embodimentof a shielded electrical cable;

FIG. 22 a-22 d are front cross-sectional views of four other exemplaryembodiments of a shielded electrical cable;

FIG. 23 a-23 d are front cross-sectional views of four other exemplaryembodiments of a shielded electrical cable;

FIG. 24 a is a perspective view of an example cable construction; and

FIG. 24 b is a cross section view of the example cable construction ofFIG. 24 a.

In the specification, a same reference numeral used in multiple figuresrefers to the same or similar elements having the same or similarproperties and functionalities.

DETAILED DESCRIPTION

The present invention generally relates to cables that include aplurality of spaced apart conductor sets and one or more EMI absorbinglayers for preventing or reducing cross talk between neighboringconductor sets by primarily absorbing the electromagnetic field.

FIG. 1 is a schematic three-dimensional view of a shielded electricalcable 2 that includes a plurality of conductor sets 4 spaced apart fromeach other along all or a portion of a width, w, of cable 2 along they-axis and extend along a length, L, of cable 2 along the x-axis. Cable2 may be arranged generally in a planar configuration as illustrated inFIG. 1 or may be folded at one or more places along its length and/orwidth into a folded configuration. In some cases, some parts of cable 2may be arranged in a planar configuration and other parts of the cablemay be folded. In some cases, at least one of the conductor sets 4 ofcable 2 includes two insulated conductors 6 extending along the length,L, of cable 2 where each insulated conductor includes a conductor 6 asurrounded by an insulator 6 b. The two insulated conductors 6 ofconductor sets 4 may be arranged substantially parallel along all or aportion of the length, L, of the cable 2. Insulated conductors 6 mayinclude insulated signal wires, insulated power wires, or insulatedground wires. Two shielding films 8 are disposed on opposite first andsecond sides of the cable 2.

The first and second shielding films 8 are arranged so that, intransverse cross section, cable 2 includes cover regions 14 and pinchedregions 18. In the cover regions 14 of the cable 2, cover portions 7 ofthe first and second shielding films 8 in transverse cross sectionsubstantially surround each conductor set 4. For example, cover portionsof the shielding films may collectively encompass at least 75%, or atleast 80, or at least 85% or at least 90% of the perimeter of any givenconductor set. Pinched portions 9 of the first and second shieldingfilms form the pinched regions 18 of cable 2 on each side of eachconductor set 4. In the pinched regions 18 of the cable 2, one or bothof the shielding films 8 are deflected, bringing the pinched portions 9of the shielding films 8 into closer proximity. In some cases, asillustrated in FIG. 1, both of the shielding films 8 are deflected inthe pinched regions 18 to bring the pinched portions 9 into closerproximity. In some cases, one of the shielding films may remainrelatively flat in the pinched regions 18 when the cable is in a planaror unfolded configuration, and the other shielding film on the oppositeside of the cable may be deflected to bring the pinched portions of theshielding film into closer proximity.

The conductors and/or ground wires may include any suitable conductivematerial and may have a variety of cross sectional shapes and sizes. Forexample, in cross section, the conductors and/or ground wires may becircular, oval, rectangular or any other shape. One or more conductorsand/or ground wires in a cable may have one shape and/or size thatdiffers from other one or more conductors and/or ground wires in thecable. The conductors and/or ground wires may be solid or strandedwires. All of the conductors and/or ground wires in a cable may bestranded, all may be solid, or some may be stranded and some solid.Stranded conductors and/or ground wires may take on different sizesand/or shapes. The connectors and/or ground wires may be coated orplated with various metals and/or metallic materials, including gold,silver, tin, and/or other materials.

The material used to insulate the conductors of the conductor sets maybe any suitable material that achieves the desired electrical propertiesof the cable. In some cases, the insulation used may be a foamedinsulation which includes air to reduce the dielectric constant and theoverall thickness of the cable. One or both of the shielding films mayinclude a conductive layer and a non-conductive polymeric layer. Theconductive layer may include any suitable conductive material, includingbut not limited to copper, silver, aluminum, gold, and alloys thereof.The shielding films may have a thickness in the range of 0.01 mm to 0.05mm and the overall thickness of the cable may be less than 2 mm or lessthan 1 mm.

Cable 2 may also include an adhesive layer 10 disposed between shieldingfilms 8 at least between the pinched portions 9. Adhesive layer 10 bondsthe pinched portions 9 of the shielding films 8 to each other in thepinched regions 18 of the cable 2. The adhesive layer 10 may or may notbe present in the cover region 14 of the cable 2.

In some cases, conductor sets 4 have a substantiallycurvilinearly-shaped envelope or perimeter in transverse cross-section(the yz-plane), and shielding films 8 are disposed around conductor sets4 such as to substantially conform to and maintain the cross-sectionalshape along at least part of, and preferably along substantially all of,the length L of cable 2. Maintaining the cross-sectional shape maintainsthe electrical characteristics of conductor sets 4 as intended in thedesign of conductor sets 4. This is an advantage over some conventionalshielded electrical cables where disposing a conductive shield around aconductor set changes the cross-sectional shape of the conductor set.

Although in the embodiment illustrated in FIG. 1, each conductor set 4has two insulated conductors 6, in other embodiments, some or all of theconductor sets may include only one insulated conductor, or may includemore than two insulated conductors 6. For example, an alternativeshielded electrical cable similar in design to that of FIG. 1 mayinclude one conductor set that has eight insulated conductors 6, oreight conductor sets each having only one insulated conductor 6. Thisflexibility in arrangements of conductor sets and insulated conductorsallows the disclosed shielded electrical cables to be configured in waysthat are suitable for a wide variety of intended applications. Forexample, the conductor sets and insulated conductors may be configuredto form: a multiple twinaxial cable, i.e., multiple conductor sets eachhaving two insulated conductors; a multiple coaxial cable, i.e.,multiple conductor sets each having only one insulated conductor; orcombinations thereof. In some embodiments, a conductor set may furtherinclude a conductive shield (not shown) disposed around the one or moreinsulated conductors, and an insulative jacket (not shown) disposedaround the conductive shield.

In the embodiment illustrated in FIG. 1, shielded electrical cable 2further includes optional ground conductors 12. Ground conductors 12 mayinclude ground wires or drain wires. Ground conductors 12 can be spacedapart from and extend in substantially the same direction as insulatedconductors 6. Shielding films 8 can be disposed around ground conductors12. The adhesive layer 10 may bond shielding films 8 to each other inthe pinched portions 9 on both sides of ground conductors 12. Groundconductors 12 may electrically contact at least one of the shieldingfilms 8.

Shielded electrical cable 2 further and optionally includes EMIabsorbing layers 15 disposed on both sides of cable 2. EMI absorbinglayers 15 attenuate the electromagnetic field primarily by absorbing thefield. Shielding films 8 attenuate the electromagnetic field primarilyby reflecting the field. In general, cable 2 can have no or one or moreshielding films 8 and/or no or one or more EMI absorbing layers 15. Insome cases, shielding films 8 and EMI absorbing layers 15 incombination, but not individually, reduce the cross-talk betweenneighboring conductor sets 4 to an acceptable and pre-determined level.In such cases, each of shielding films 8 and EMI absorbing layers 15reduce the cross-talk to a level that is greater than the pre-determinedand desirable level, but, in combination, they reduce the cross-talk toa level that is equal to or less than the pre-determined and desirablelevel.

EMI absorbing layers 15 can include any type material that is capable ofattenuating an electromagnetic field primarily through absorption. Forexample, in some cases, the EMI absorbing material can be a dielectricmaterial having a magnetic permeability of greater than one, or greaterthan two, or greater than three, in the desired frequency range, andwhich exhibits a non-negligible magnetic loss tangent. Examples of EMIabsorbing materials include EMI Absorbers AB-2000 Series or EMIAbsorbers AB-5000 Series, both commercially available from 3M Company,St. Paul, Minn. EMI Absorbers AB-2000 Series includes a thin, flexiblebacking made of silicone rubber and magnetic materials, with an acrylicpressure-sensitive adhesive. EMI Absorbers AB-5000 Series includes aflexible soft metal flake filler in polymer resin with an acrylicadhesive system and removable liner. Examples of EMI absorbing materialsinclude ferromagnetic materials such as, e.g., ferrite materials. Aferrite material may be formed of non-conductive, Fe-oxide compoundsincluding Fe₂O₃ and/or Fe₃O₄ as well as other metal oxides. In somecases, an EMI absorbing material can be formed as polymeric resin thatincludes ferromagnetic powder. In some cases, the composition andstructure of EMI absorbing material can be selected to absorbelectromagnetic waves at one or more frequency generally associated withthe electromagnetic field generated by the conductor sets. In somecases, the composite EMI absorbing material can absorb electromagneticwaves over a range of frequencies.

The cross-sectional views of FIGS. 2 a-2 g may represent variousshielded electrical cables, or portions of cables. In FIG. 2 a, shieldedelectrical cable 102 a includes a single conductor set 104. Conductorset 104 extends along the length of the cable along the x-axis ordirection and has only a single insulated conductor 106. If desired, thecable 102 a may be made to include multiple conductor sets 104 spacedapart from each other across a width of the cable 102 a along the y-axisand extending along the length of the cable. Two shielding films 108 aredisposed on opposite sides of the cable. Furthermore, two EMI absorbinglayers 115 are disposed on the shielding films on opposite first andsecond sides of the cable. Furthermore, two EMI absorbing layers 115 aredisposed on the shielding films on opposite sides of the cable. Thecable 102 a includes a cover region 114 and pinched regions 118. In thecover region 114 of the cable 102 a, the shielding films 108 includecover portions 107 that cover the conductor set 104. In transverse crosssection in the yz-plane, the cover portions 107, in combination,substantially surround the conductor set 104. In the pinched regions 118of the cable 102 a, the shielding films 108 include pinched portions 109on each side of the conductor set 104.

In the exemplary cable 102 a, the shielding films are disposed betweenthe EMI absorbing layers and the conductor sets. In some cases, the EMIabsorbing layers can be disposed between the shielding films and theconductor sets. In some cases, not shown expressly in FIG. 2 a, ashielding film may be disposed between two EMI absorbing layers on thesame side of the cable, or an EMI absorbing layer may be disposedbetween two shielding films on the same side of the cable. In somecases, the cable can include alternating layers of shielding films andEMI absorbing layers.

An optional adhesive layer 110 may be disposed between shielding films108. Shielded electrical cable 102 a further includes optional groundconductors 112. Ground conductors 112 are spaced apart from and extendin substantially the same direction (x-axis) as insulated conductor 106.Conductor set 104 and ground conductors 112 can be arranged so that theylie generally in a plane, such as the xy-plane, as illustrated in FIG. 2a.

Second cover portions 113 of shielding films 108 are disposed around,and cover, the ground conductors 112. The adhesive layer 110 may bondthe shielding films 108 to each other on both sides of ground conductors112. Ground conductors 112 may electrically contact at least one ofshielding films 108. In FIG. 2 a, insulated conductor 106 and shieldingfilms 108 are effectively arranged in a coaxial cable configuration withextensions on both sides of the conductor set. The coaxial cableconfiguration of FIG. 2 a can be used in a single ended circuitarrangement.

As illustrated in the transverse cross sectional view of FIG. 2 a, thereis a maximum separation, D, between the cover portions 107 of theshielding films 108, and there is a minimum separation, d₁, between thepinched portions 109 of the shielding films 108.

FIG. 2 a shows the adhesive layer 110 disposed between the pinchedportions 109 of the shielding films 108 in the pinched regions 118 ofthe cable 102 a and disposed between the cover portions 107 of theshielding films 108 and the insulated conductor 106 in the cover region114 of the cable 102 a. In this arrangement, the adhesive layer 110bonds the pinched portions 109 of the shielding films 108 together inthe pinched regions 118 of the cable, and bonds the cover portions 107of the shielding films 108 to the insulated conductor 106 in the coverregion 114 of the cable 102 a.

Shielded cable 102 b of FIG. 2 b is similar to cable 102 a of FIG. 2 a,with similar elements identified by similar reference numerals. In FIG.2 b, the optional adhesive layer 110 is not present between the coverportions 107 of the shielding films 108 and the insulated conductor 106in the cover region 114 of the cable 102 b. In this arrangement, theadhesive layer 110 bonds the pinched portions 109 of the shielding films108 together in the pinched regions 118 of the cable, but the adhesivelayer 110 does not bond cover portions 107 of the shielding films 108 tothe insulated conductor 106 in the cover regions 114 of the cable 102 b.

Referring to FIG. 2 c, shielded electrical cable 202 c is similar toshielded electrical cable 102 a of FIG. 2 a. Cable 202 c has a singleconductor set 204 which has two insulated conductors 206. If desired,the cable 202 c may be made to include multiple conductor sets 204spaced part across a width of the cable 202 c and extending along alength of the cable. Insulated conductors 206 are arranged generally ina single plane (the xy-plane) and effectively in a twinaxialconfiguration. The twin axial cable configuration of FIG. 2 c can beused in a differential pair circuit arrangement or in a single endedcircuit arrangement.

Two shielding films 208 and EMI absorbing layers 115 are disposed onopposite sides of conductor set 204. The cable 202 c includes a coverregion 214 and pinched regions 218. In the cover region 214 of the cable202 c, the shielding films 208 include cover portions 207 that cover theconductor set 204. In transverse cross section, the cover portions 207,in combination, substantially surround the conductor set 204. In thepinched regions 218 of the cable 202 c, the shielding films 208 includepinched portions 209 on each side of the conductor set 204.

An optional adhesive layer 210 c may be disposed between shielding films208. Shielded electrical cable 202 c further includes optional groundconductors 212. Ground conductors 212 are spaced apart from, and extendin substantially the same direction as, insulated conductors 206 alongthe x-axis. Conductor set 204 and ground conductors 212 can be arrangedso that they lie generally in a plane, such as the xy-plane, asillustrated in FIG. 2 c.

As illustrated in the cross section of FIG. 2 c, there is a maximumseparation, D, between the cover portions 207 of the shielding films208; there is a minimum separation, d₁, between the pinched portions 209of the shielding films 208; and there is a minimum separation, d₂,between the shielding films 208 between the insulated conductors 206.Cable 202 c can be characterized by a maximum separation, D, between thecover portions 107 of the shielding films 108, a minimum separation, d₂,between the cover portions 107 of the shielding films 108, and a minimumseparation, d₁, between the pinched portions 109 of the shielding films108. In some cases, the ratio d₁/D is less than 0.25 or less than 0.1.In some cases, d₂/D is greater than 0.33.

FIG. 2 c shows the adhesive layer 210 c disposed between the pinchedportions 209 of the shielding films 208 in the pinched regions 218 ofthe cable 202 and disposed between the cover portions 207 of theshielding films 208 and the insulated conductors 206 in the cover region214 of the cable 202 c. In this arrangement, the adhesive layer 210 cbonds the pinched portions 209 of the shielding films 208 together inthe pinched regions 218 of the cable 202 c, and also bonds the coverportions 207 of the shielding films 208 to the insulated conductors 206in the cover region 214 of the cable 202 c.

Shielded cable 202 d of FIG. 2 d is similar to cable 202 c of FIG. 2 c,with similar elements identified by similar reference numerals, exceptthat in cable 202 d the optional adhesive layer 210 d is not presentbetween the cover portions 207 of the shielding films 208 and theinsulated conductors 206 in the cover region 214 of the cable. In thisarrangement, the adhesive layer 210 d bonds the pinched portions 209 ofthe shielding films 208 together in the pinched regions 218 of thecable, but does not bond the cover portions 207 of the shielding films208 to the insulated conductors 206 in the cover region 214 of the cable202 d.

Referring now to FIG. 2 e, we see there a transverse cross-sectionalview of a shielded electrical cable 302 similar in many respects to theshielded electrical cable 102 a of FIG. 2 a. However, where cable 102 aincludes a single conductor set 104 having only a single insulatedconductor 106, cable 302 includes a single conductor set 304 that hastwo insulated conductors 306 extending along the length of the cable 302along the x-axis or direction. Cable 302 may be made to have multipleconductor sets 304 spaced apart from each other across a width of thecable 302 and extending along a length of the cable 302. Insulatedconductors 306 are arranged effectively in a twisted pair cablearrangement, whereby insulated conductors 306 twist around each otherand extend along the length of the cable 302 along the x-axis ordirection.

FIG. 2 f depicts another shielded electrical cable 402 that is alsosimilar in many respects to the shielded electrical cable 102 a of FIG.2 a. However, where cable 102 a includes a single conductor set 104having only a single insulated conductor 106, cable 402 includes asingle conductor set 404 that has four insulated conductors 406extending along the length of the cable 402 along the x-axis ordirection. The cable 402 may be made to have multiple conductor sets 404spaced apart from each other across a width of the cable 302 along they-axis and extending along the length of the cable 302 along the x-axis.

Insulated conductors 406 are arranged effectively in a quad cablearrangement, whereby insulated conductors 406 may or may not twistaround each other as insulated conductors 406 extend along the length ofthe cable 402 along the x-axis.

Referring back to FIGS. 2 a-2 f, further embodiments of shieldedelectrical cables may include a plurality of spaced apart conductor sets104, 204, 304, or 404, or combinations thereof, arranged generally in asingle plane. Optionally, the shielded electrical cables may include aplurality of ground conductors 112 spaced apart from, and extendinggenerally in the same direction as, the insulated conductors of theconductor sets. In some configurations, the conductor sets and groundconductors can be arranged generally in a single plane. FIG. 2 gillustrates an exemplary embodiment of such a shielded electrical cable.

Referring to FIG. 2 g, shielded electrical cable 502 includes aplurality of spaced apart conductor sets 504 a, 504 b arranged generallyin the xy-plane where each conductor set includes one or two insulatedconductors 506. Shielded electrical cable 504 further includes optionalground conductors 112 disposed between conductor sets 504 a, 504 b andat both sides or edges of shielded electrical cable 502.

First and second shielding films 508 are disposed on opposite first andsecond sides of the cable 502 and are arranged so that, in transversecross section in the yz-plane, the cable 502 includes cover regions 524and pinched regions 528. In the cover regions 524 of the cable, coverportions 517 of the first and second shielding films 508 in transversecross section substantially surround each conductor set 504 a, 504 b.For example, the cover portions of the first and second shielding filmsin combination substantially surround each conductor set by encompassingat least 70% of a periphery of each conductor set. Pinched portions 519of the first and second shielding films 508 form the pinched regions 518on two sides of each conductor set 504 a, 504 b.

The shielding films 508 are disposed around ground conductors 112. Anoptional adhesive layer 510 is disposed between shielding films 208 andbonds the pinched portions 519 of the shielding films 508 to each otherin the pinched regions 528 on both sides of each conductor set 504 a,504 b. Shielded electrical cable 502 includes a combination of coaxialcable arrangements (conductor sets 504 a) and a twinaxial cablearrangement (conductor set 504 b) and may therefore be referred to as ahybrid cable arrangement. In some cases, cable 502 can include one ormore EMI absorbing layers, not expressly shown in FIG. 2 g, disposed onthe conductor sets on one or both sides of the cable.

The shielding films used in the disclosed shielded cables can have avariety of configurations and can be made in a variety of ways. FIGS. 7a-7 d illustrate four exemplary embodiments of a shielded electricalcable according to aspects of the present invention. FIGS. 3 a-3 dillustrate various examples of constructions of the shielding films ofthe shielded electrical cables. In one aspect, at least one of theshielding films may include a conductive layer and a non-conductivepolymeric layer. The conductive layer may include any suitableconductive material, including but not limited to copper, silver,aluminum, gold, and alloys thereof. The non-conductive polymeric layermay include any suitable polymeric material, including but not limitedto polyester, polyimide, polyamide-imide, polytetrafluoroethylene,polypropylene, polyethylene, polyphenylene sulfide, polyethylenenaphthalate, polycarbonate, silicone rubber, ethylene propylene dienerubber, polyurethane, acrylates, silicones, natural rubber, epoxies, andsynthetic rubber adhesive. The non-conductive polymeric layer mayinclude one or more additives and/or fillers to provide propertiessuitable for the intended application. In another aspect, at least oneof the shielding films may include a laminating adhesive layer disposedbetween the conductive layer and the non-conductive polymeric layer. Forshielding films that have a conductive layer disposed on anon-conductive layer, or that otherwise have one major exterior surfacethat is electrically conductive and an opposite major exterior surfacethat is substantially non-conductive, the shielding film may beincorporated into the shielded cable in several different orientationsas desired. In some cases, for example, the conductive surface may facethe conductor sets of insulated wires and ground wires, and in somecases the non-conductive surface may face those components. In caseswhere two shielding films are used on opposite sides of the cable, thefilms may be oriented such that their conductive surfaces face eachother and each face the conductor sets and ground wires, or they may beoriented such that their non-conductive surfaces face each other andeach face the conductor sets and ground wires, or they may be orientedsuch that the conductive surface of one shielding film faces theconductor sets and ground wires, while the non-conductive surface of theother shielding film faces conductor sets and ground wires from theother side of the cable.

In some cases, at least one of the shielding films may include astand-alone conductive film, such as a compliant or flexible metal foil.The construction of the shielding films may be selected based on anumber of design parameters suitable for the intended application, suchas, e.g., flexibility, electrical performance, and configuration of theshielded electrical cable (such as, e.g., presence and location ofground conductors). In some cases, the shielding films have anintegrally formed construction. In some cases, the shielding films mayhave a thickness in the range of 0.01 mm to 0.05 mm. The shielding filmsdesirably provide isolation, shielding, and precise spacing between theconductor sets, and allow for a more automated and lower cost cablemanufacturing process. In addition, the shielding films are conductivesheets and prevent a phenomenon known as “signal suck-out” or resonance,whereby high signal attenuation occurs at a particular frequency range.This phenomenon typically occurs in conventional shielded electricalcables where a conductive shield is a ribbon wrapped around a conductorset.

FIG. 3 a is a cross sectional view across a width of a shieldedelectrical cable 802 that shows a single conductor set 804. Conductorset 804 includes two insulated conductors 806 that extend along a lengthof the cable 802 along the x-axis. Cable 802 may include multipleconductor sets 804 spaced apart from each other across the width of thecable 802 along the y-axis. Two shielding films 808 are disposed onopposite sides of the cable 802 where each shielding film includes aconductive layer 808 a disposed on a non-conductive polymeric layer 808b. Non-conductive polymeric layer 808 b faces insulated conductors 806.Conductive layer 808 a may be deposited onto non-conductive polymericlayer 808 b using any suitable method. In transverse cross section inthe yz-plane, cover portions 807 of the shielding films 808, incombination, substantially surround the conductor set 804 in the coverregion 814 of the cable 802. For example, the cover portions of thefirst and second shielding films in combination substantially surroundeach conductor set by encompassing at least 70% of a periphery of eachconductor set. Pinched portions 809 of the shielding films 808 formpinched regions 818 of the cable 802 on each side of the conductor set804.

Shielding films 808 may include optional adhesive layers 810 a, 810 bthat bond the pinched portions 809 of the shielding films 808 to eachother in the pinched regions 818 of the cable 802. Adhesive layer 810 ais disposed on one of the non-conductive polymeric layers 808 b andadhesive layer 810 b is disposed on another of the non-conductivepolymeric layers 808 b. The adhesive layers 810 a, 810 b may or may notbe present in the cover region 814 of the cable 802. If present, theadhesive layers 810 a, 810 b may extend fully or partially across thewidth of the cover portions 807 of the shielding film 808, bonding thecover portions 807 of the shielding films 808 to the insulatedconductors 806.

In this example, insulated conductors 806 and shielding films 808 arearranged generally in a single plane, such as the xy-plane, andeffectively in a twinaxial configuration which may be used in a singleended circuit arrangement or a differential pair circuit arrangement.

FIG. 3 b is a cross sectional view across a width of a shieldedelectrical cable 902 that shows a single conductor set 904. Conductorset 904 includes two insulated conductors 906 that extend along a lengthof the cable 902 along the x-axis. Cable 902 may include multipleconductor sets 904 spaced apart from each other along a width of thecable 902 along the y-axis and extending along a length of the cable902. Two shielding films 908 are disposed on opposite sides of the cable902 where each shielding film includes a conductive layer 908 a disposedon a non-conductive polymeric layer 908 b. Conductive layer 908 a facesinsulated conductors 906. Conductive layer 908 a may be deposited ontonon-conductive polymeric layer 908 b using any suitable method. Intransverse cross section, cover portions 907 of the shielding films 908,in combination, substantially surround the conductor set 904 in thecover regions 914 of the cable 902. Pinched portions 909 of theshielding films 908 form pinched regions 918 of the cable 902 on eachside of the conductor set 904.

One or more optional adhesive layers 910 a, 910 b bond the pinchedportions 909 of the shielding films 908 to each other in the pinchedregions 918 on both sides of conductor set 904. The adhesive layers 910a, 910 b may extend fully or partially across the width of the coverportions 907 of the shielding film 908. Insulated conductors 906 arearranged generally in a single plane and effectively form a twinaxialcable configuration and can be used in a single ended circuitarrangement or a differential pair circuit arrangement.

FIG. 3 c is a cross sectional view across a width of a shieldedelectrical cable 1002 showing a single conductor set 1004. Conductor set1004 includes two insulated conductors 1006 that extend along a lengthof the cable 1002 along the x-axis. Cable 1002 may include multipleconductor sets 1004 spaced apart from each other along a width of thecable 1002 along the y-axis and extending along a length of the cable1002. Two shielding films 1008 are disposed on opposite sides of thecable 1002 and include cover portions 1007. In transverse cross section,the cover portions 1007, in combination, substantially surround theconductor set 1004 in a cover region 1014 of the cable 1002. Pinchedportions 1009 of the shielding films 1008 form pinched regions 1018 ofthe cable 1002 on each side of the conductor set 1004.

Cable 1002 includes one or more optional adhesive layers 1010 a, 1010 bthat bond the pinched portions 1009 of the shielding films 1008 to eachother on both sides of conductor set 1004 in the pinched regions 1018.The adhesive layers 1010 a, 1010 b may extend fully or partially acrossthe width of the cover portions 1007 of the shielding film 1008.Insulated conductors 1006 are arranged generally in a single plane, suchas the xy-plane, and effectively in a twinaxial cable configuration thatcan be used in a single ended circuit arrangement or a differential paircircuit arrangement. Shielding films 1008 include a stand-aloneconductive film.

FIG. 3 d is a cross sectional view of a shielded electrical cable 1102that shows a single conductor set 1104. Conductor set 1104 includes twoinsulated conductors 1106 which extend along a length of the cable 1102along the x-axis. Cable 1102 may include multiple conductor sets 1104spaced apart from each other along a width of the cable 1102 along they-axis and extending along a length of the cable 1102. Two shieldingfilms 1108 are disposed on opposite sides of the cable 1102 and includecover portions 1107. In transverse cross section, the cover portions1107, in combination, substantially surround conductor set 1104 in acover region 1114 of the cable 1102. Pinched portions 1109 of theshielding films 1108 form pinched regions 1118 of the cable 1102 on eachside of the conductor set 1104.

Shielding films 1108 include one or more optional adhesive layers 1110 aand 1110 b that bond the pinched portions 1109 of the shielding films1108 to each other in the pinched regions 1118 on both sides ofconductor set 1104. The adhesive layer 1010 a, 1010 b may extend fullyor partially across the width of the cover portions 1107 of theshielding film 1108.

Insulated conductors 1106 are arranged generally in a single plane, suchas the xy-plane, and effectively in a twinaxial cable configuration. Thetwinaxial cable configuration can be used in a single ended circuitarrangement or a differential circuit arrangement. Shielding films 1108include a conductive layer 1108 a, a non-conductive polymeric layer 1108b, and a laminating adhesive layer 1108 c disposed between conductivelayer 1108 a and non-conductive polymeric layer 1108 b, therebylaminating conductive layer 1108 a to non-conductive polymeric layer1108 b. Conductive layer 1108 a faces insulated conductors 1106.

As discussed elsewhere herein, adhesive material may be used in thecable construction to bond one or two shielding films to one, some, orall of the conductor sets at cover regions of the cable, and/or adhesivematerial may be used to bond two shielding films together at pinchedregions of the cable. A layer of adhesive material may be disposed on atleast one shielding film, and in cases where two shielding films areused on opposite sides of the cable, a layer of adhesive material may bedisposed on both shielding films. In the latter cases, the adhesive usedon one shielding film is preferably the same as, but may if desired bedifferent from, the adhesive used on the other shielding film. A givenadhesive layer may include an electrically insulative adhesive, and mayprovide an insulative bond between two shielding films. Furthermore, agiven adhesive layer may provide an insulative bond between at least oneof shielding films and insulated conductors of one, some, or all of theconductor sets, and between at least one of shielding films and one,some, or all of the ground conductors (if any). Alternatively, a givenadhesive layer may include an electrically conductive adhesive, and mayprovide a conductive bond between two shielding films. Furthermore, agiven adhesive layer may provide a conductive bond between at least oneof shielding films and one, some, or all of the ground conductors (ifany). Suitable conductive adhesives include conductive particles toprovide the flow of electrical current. The conductive particles can beany of the types of particles currently used, such as spheres, flakes,rods, cubes, amorphous, or other particle shapes. They may be solid orsubstantially solid particles such as carbon black, carbon fibers,nickel spheres, nickel coated copper spheres, metal-coated oxides,metal-coated polymer fibers, or other similar conductive particles.These conductive particles can be made from electrically insulatingmaterials that are plated or coated with a conductive material such assilver, aluminum, nickel, or indium tin-oxide. The metal-coatedinsulating material can be substantially hollow particles such as hollowglass spheres, or may comprise solid materials such as glass beads ormetal oxides. The conductive particles may be on the order of severaltens of microns to nanometer sized materials such as carbon nanotubes.Suitable conductive adhesives may also include a conductive polymericmatrix.

When used in a given cable construction, an adhesive layer is preferablysubstantially conformable in shape relative to other elements of thecable, and conformable with regard to bending motions of the cable. Insome cases, a given adhesive layer may be substantially continuous,e.g., extending along substantially the entire length and width of agiven major surface of a given shielding film. In some cases, theadhesive layer may be substantially discontinuous. For example, theadhesive layer may be present only in some portions along the length orwidth of a given shielding film. A discontinuous adhesive layer may forexample include a plurality of longitudinal adhesive stripes that aredisposed, e.g., between the pinched portions of the shielding films onboth sides of each conductor set and between the shielding films besidethe ground conductors (if any). A given adhesive material may be orinclude at least one of a pressure sensitive adhesive, a hot meltadhesive, a thermoset adhesive, and a curable adhesive. An adhesivelayer may be configured to provide a bond between shielding films thatis substantially stronger than a bond between one or more insulatedconductor and the shielding films. This may be achieved, e.g., byappropriate selection of the adhesive formulation. An advantage of thisadhesive configuration is to allow the shielding films to be readilystrippable from the insulation of insulated conductors. In other cases,an adhesive layer may be configured to provide a bond between shieldingfilms and a bond between one or more insulated conductor and theshielding films that are substantially equally strong. An advantage ofthis adhesive configuration is that the insulated conductors areanchored between the shielding films. When a shielded electrical cablehaving this construction is bent, this allows for little relativemovement and therefore reduces the likelihood of buckling of theshielding films. Suitable bond strengths may be chosen based on theintended application. In some cases, a conformable adhesive layer may beused that has a thickness of less than about 0.13 mm. In exemplaryembodiments, the adhesive layer has a thickness of less than about 0.05mm.

A given adhesive layer may conform to achieve desired mechanical andelectrical performance characteristics of the shielded electrical cable.For example, the adhesive layer may conform to be thinner between theshielding films in areas between conductor sets, which increases atleast the lateral flexibility of the shielded cable. This may allow theshielded cable to be placed more easily into a curvilinear outer jacket.In some cases, an adhesive layer may conform to be thicker in areasimmediately adjacent the conductor sets and substantially conform to theconductor sets. This may increase the mechanical strength and enableforming a curvilinear shape of shielding films in these areas, which mayincrease the durability of the shielded cable, for example, duringflexing of the cable. In addition, this may help to maintain theposition and spacing of the insulated conductors relative to theshielding films along the length of the shielded cable, which may resultin more uniform impedance and superior signal integrity of the shieldedcable.

A given adhesive layer may conform to effectively be partially orcompletely removed between the shielding films in areas betweenconductor sets, e.g., in pinched regions of the cable. As a result, theshielding films may electrically contact each other in these areas,which may increase the electrical performance of the cable. In somecases, an adhesive layer may conform to effectively be partially orcompletely removed between at least one of the shielding films and theground conductors. As a result, the ground conductors may electricallycontact at least one of shielding films in these areas, which mayincrease the electrical performance of the cable. Even in cases where athin layer of adhesive remains between at least one of shielding filmsand a given ground conductor, asperities on the ground conductor maybreak through the thin adhesive layer to establish electrical contact asintended.

FIGS. 4 a-4 c are cross sectional views of three exemplary embodimentsof a shielded electrical cable which illustrate examples of theplacement of ground conductors in the shielded electrical cables. Anaspect of a shielded electrical cable is proper grounding of the shieldand such grounding can be accomplished in a number of ways. In somecases, a given ground conductor can electrically contact at least one ofthe shielding films such that grounding the given ground conductor alsogrounds the shielding films. Such a ground conductor may also bereferred to as a “drain wire”. Electrical contact between the shieldingfilm and the ground conductor may be characterized by a relatively lowDC resistance, e.g., a DC resistance of less than 10 ohms, or less than2 ohms, or of substantially 0 ohms. In some cases, a given groundconductor does not electrically contact the shielding films, but may bean individual element in the cable construction that is independentlyterminated to any suitable individual contact element of any suitabletermination component, such as, e.g., a conductive path or other contactelement on a printed circuit board, paddle board, or other device. Sucha ground conductor may also be referred to as a “ground wire”. FIG. 4 aillustrates an exemplary shielded electrical cable in which groundconductors are positioned external to the shielding films. FIGS. 4 b-4 cillustrate embodiments in which the ground conductors are positionedbetween the shielding films, and may be included in the conductor set.One or more ground conductors may be placed in any suitable positionexternal to the shielding films, between the shielding films, or acombination of both.

Referring to FIG. 4 a, a shielded electrical cable 1202 includes asingle conductor set 1204 that extends along a length of the cable 1202along the x-axis. Conductor set 1204 includes two insulated conductors1206, i.e., one pair of insulated conductors. Cable 1202 may includemultiple conductor sets 1204 spaced apart from each other across a widthof the cable along the y-axis and extending along a length of the cable1202. Two shielding films 1208 are disposed on opposite first and secondsides of the cable 1202 and include cover portions 1207 and pinchedportions 1209. In transverse cross section, the cover portions 1207, incombination, substantially surround conductor set 1204. An optionaladhesive layer 1210 is disposed between pinched portions 1209 of theshielding films 1208 and bonds shielding films 1208 to each other onboth sides of conductor set 1204. Insulated conductors 1206 are arrangedgenerally in a single plane, such as the xy-plane, and effectively in atwinaxial cable configuration that can be used in a single ended circuitarrangement or a differential pair circuit arrangement. Shieldedelectrical cable 1202 further includes a plurality of ground conductors1212 positioned external to shielding films 1208. Ground conductors 1212are placed over, under, and on both sides of conductor set 1204.Optionally, shielded electrical cable 1202 includes protective films1220 surrounding shielding films 1208 and ground conductors 1212.Protective films 1220 include a protective layer 1220 a and an adhesivelayer 1220 b bonding protective layer 1220 a to shielding films 1208 andground conductors 1212. Alternatively, shielding films 1208 and groundconductors 1212 may be surrounded by an outer conductive shield, suchas, e.g., a conductive braid, and an outer insulative jacket (notshown). In some cases, at least one protective layer 1220 a and adhesivelayer 1220 b can be electrically conductive

Referring to FIG. 4 b, shielded electrical cable 1302 includes a singleconductor set 1304 that extends along a length of cable 1302 along thex-axis. Conductor set 1304 includes two insulated conductors 1306. Cable1302 may include multiple conductor sets 1304 spaced apart from eachother across a width of the cable 1302 along the y-axis and extendingalong the length of the cable 1302. Two shielding films 1308 aredisposed on opposite first and second sides of the cable 1302 andinclude cover portions 1307 and pinched portions 1309. In transversecross section, cover portions, in combination, substantially surroundconductor set 1304. An optional adhesive layer 1310 is disposed betweenpinched portions 1309 of the shielding films 1308 and bonds shieldingfilms 1308 to each other on both sides of conductor set 1304. Insulatedconductors 1306 are arranged generally in a single plane and effectivelyin a twinaxial or differential pair cable arrangement. Shieldedelectrical cable 1302 further includes a plurality of ground conductors1312 positioned between shielding films 1308. Two of the groundconductors 1312 are included in conductor set 1304, and two of theground conductors 1312 are spaced apart from conductor set 1304.

Referring to FIG. 4 c, shielded electrical cable 1402 includes a singleconductor set 1404 that extends along a length of cable 1402 along thex-axis. Conductor set 1404 includes two insulated conductors 1406. Cable1402 may include multiple conductor sets 1304 spaced apart from eachother across a width of the cable 1402 along the y-axis and extendingalong the length of the cable 1402. Two shielding films 1408 aredisposed on opposite first and second sides of the cable 1402 andinclude cover portions 1407 and pinched portions 1409. In transversecross section, the cover portions 1407, in combination, substantiallysurround conductor set 1404. An optional adhesive layer 1410 is disposedbetween pinched portions 1409 of the shielding films 1408 and bondsshielding films 1408 to each other on both sides of conductor set 1404.Insulated conductors 1406 are arranged generally in a single plane andeffectively in a twinaxial or differential pair cable arrangement.Shielded electrical cable 1402 further includes a plurality of groundconductors 1412 positioned between shielding films 1408. All of theground conductors 1412 are included in conductor set 1404. Two of theground conductors 1412 and insulated conductors 1406 are arrangedgenerally in a single plane, such as the xy-plane. Shielded electricalcable 1402 further includes EMI absorbing layers 1450 disposed onshielding films 1408 and conductor set 1404 on both sides of the cable.

FIGS. 5 a-5 g illustrate an exemplary method of making a shieldedelectrical cable that may be substantially the same as that shown inFIG. 1.

In the step illustrated in FIG. 5 a, insulated conductors 6 are formedusing any suitable method, such as, e.g., extrusion, or are otherwiseprovided. Insulated conductors 6 include conductor 6 a surrounded byinsulator 6 b and may be formed of any suitable length. Insulatedconductors 6 may then be provided as such or cut to a desired length.Ground conductors 12 (see FIG. 5 c) may be formed and provided in asimilar fashion.

In the step illustrated in FIG. 5 b, one or more shielding films 8 areformed. A single layer or multilayer web may be formed using anysuitable method, such as, e.g., continuous wide web processing. Eachshielding film 8 may be formed of any suitable length. The shieldingfilm 8 may then be provided as such or cut to a desired length and/orwidth. The shielding film 8 may be pre-formed to have transverse partialfolds to increase flexibility in the longitudinal direction. One or bothof the shielding films 8 may include a conformable adhesive layer 10,which may be formed on the shielding film 8 using any suitable method,such as, e.g., laminating, coating or sputtering.

In the step illustrated in FIG. 5 c, a plurality of insulated conductors6, ground conductors 12, and shielding films 8 are provided. A formingtool 24 is provided. Forming tool 24 includes a pair of forming rolls 26a, 26 b having a shape corresponding to a desired cross-sectional shapeof the shielded electrical cable 2, the forming tool also including abite 28. Insulated conductors 6, ground conductors 12, and shieldingfilms 8 are arranged according to the configuration of desired shieldedelectrical cable 2, such as any of the cables shown and/or describedherein, and positioned in proximity to forming rolls 26 a, 26 b, afterwhich they are concurrently fed into bite 28 of forming rolls 26 a, 26 band disposed between forming rolls 26 a, 26 b. Forming tool 24 formsshielding films 8 around conductor sets 4 and ground conductor 12 andbonds shielding films 8 to each other on both sides of each conductorset 4 and ground conductors 12. Heat may be applied to facilitatebonding. Although in this embodiment, forming shielding films 8 aroundconductor sets 4 and ground conductor 12 and bonding shielding films 8to each other on both sides of each conductor set 4 and groundconductors 12 occur in a single operation, in other embodiments, thesesteps may occur in separate operations.

Other layers can be included in the arrangement that is fed into bite 28of forming rolls 26 a and 26 b. For example, one or more EMI absorbinglayer, one or more protective layers, and/or one or more jacket layerscan be included in the arrangement and fed into bite 28.

FIG. 5 d illustrates shielded electrical cable 2 as it is formed byforming tool 24. In the optional step illustrated in FIG. 5 e,longitudinal splits 18 are formed between conductor sets 4. Splits 18may be formed in shielded electrical cable 2 using any suitable method,such as, e.g., laser cutting or punching.

In another optional step illustrated in FIG. 5 f, shielding films 8 ofshielded electrical cable 2 may be folded lengthwise along the pinchedregions multiple times into a bundle, and an outer conductive shield 30may be provided around the folded bundle using any suitable method. Anouter jacket 32 may also be provided around outer conductive shield 30as schematically illustrated in FIG. 5 g, using any suitable method,such as, e.g., extrusion. In some embodiments, the outer conductiveshield 30 may be omitted and the outer jacket 32 may be provided aroundthe folded shielded cable.

FIGS. 6 a-6 c illustrate a detail of an exemplary method of making ashielded electrical cable. FIGS. 6 a-6 c illustrate how one or moreadhesive layers may be conformably shaped during the forming and bondingof the shielding films.

In the step illustrated in FIG. 6 a, an insulated conductor 1606, aground conductor 1612 spaced apart from insulated conductor 1606, andtwo shielding films 1608 are provided. Shielding films 1608 each includea conformable adhesive layer 1610. In the steps illustrated in FIGS. 6b-6 c, shielding films 1608 are formed around insulated conductor 1606and ground conductor 1612 and bonded to each other. Initially, asillustrated in FIG. 6 b, adhesive layers 1610 still have their originalthickness. As the forming and bonding of shielding films 1608 proceeds,conformable adhesive layers 1610 conform to achieve desired mechanicaland electrical performance characteristics of shielded electrical cable1602 (FIG. 6 c).

As illustrated in FIG. 6 c, adhesive layers 1610 conform to be thinnerbetween shielding films 1608 on both sides of insulated conductor 1606and ground conductor 1612; a portion of adhesive layers 1610 displacesaway from these areas. Further, conformable adhesive layers 1610 conformto be thicker in areas immediately adjacent insulated conductor 1606 andground conductor 1612, and substantially conform to insulated conductor1606 and ground conductor 1612; a portion of adhesive layers 1610displaces into these areas. Further, conformable adhesive layers 1610conform to effectively be removed between shielding films 1608 andground conductor 1612; conformable adhesive layers 1610 displace awayfrom these areas such that ground conductor 1612 electrically contactsshielding films 1608.

In some approaches, a semi-rigid cable can be formed using a thickermetal or metallic material as the shielding film. For example, aluminumor other metal may be used in this approach without a polymer backingfilm. The aluminum (or other material) is passed through shaping dies tocreate corrugations in the aluminum which form cover portions andpinched portions. The insulated conductors are placed in thecorrugations that form the cover portions. If drain wires are used,smaller corrugations may be formed for the drain wires. The insulatedconductors and, optionally, drain wires, are sandwiched in betweenopposite layers of corrugated aluminum. The aluminum layers may bebonded together with adhesive or welded, for example. Connection betweenthe upper and lower corrugated aluminum shielding films could be throughthe un-insulated drain wires. Alternatively, the pinched portions of thealuminum could be embossed, pinched further and/or punched through toprovide positive contact between the corrugated shielding layers.

In exemplary embodiments, the cover regions of the shielded electricalcable include concentric regions and transition regions positioned onone or both sides of a given conductor set. Portions of a givenshielding film in the concentric regions are referred to as concentricportions of the shielding film and portions of the shielding film in thetransition regions are referred to as transition portions of theshielding film. The transition regions can be configured to provide highmanufacturability and strain and stress relief of the shieldedelectrical cable. Maintaining the transition regions at a substantiallyconstant configuration (including aspects such as, e.g., size, shape,content, and radius of curvature) along the length of the shieldedelectrical cable may help the shielded electrical cable to havesubstantially uniform electrical properties, such as, e.g., highfrequency isolation, impedance, skew, insertion loss, reflection, modeconversion, eye opening, and jitter.

Additionally, in certain embodiments, such as, e.g., embodiments whereinthe conductor set includes two insulated conductors that extend along alength of the cable that are arranged generally in a single andeffectively as a twinaxial cable that can be connected in a differentialpair circuit arrangement, maintaining the transition portion at asubstantially constant configuration along the length of the shieldedelectrical cable can beneficially provide substantially the sameelectromagnetic field deviation from an ideal concentric case for bothconductors in the conductor set. Thus, careful control of theconfiguration of this transition portion along the length of theshielded electrical cable can contribute to the advantageous electricalperformance and characteristics of the cable. FIGS. 7 a-9 b illustratevarious exemplary embodiments of a shielded electrical cable thatinclude transition regions of the shielding films disposed on one orboth sides of the conductor set.

The shielded electrical cable 1702, which is shown in cross section inFIGS. 7 a and 7 b, includes a single conductor set 1704 that extendsalong a length of the cable 1702 along the x-axis. The shieldedelectrical cable 1702 may be made to have multiple conductor sets 1704spaced apart from each other along a width of the cable 1702 along they-axis and extending along a length of the cable 1702. Although only oneinsulated conductor 1706 is shown in FIG. 7 a, multiple insulatedconductors may be included in the conductor set 1704, if desired.

The insulated conductor of a conductor set that is positioned nearest toa pinched region of the cable is considered to be an end conductor ofthe conductor set. The conductor set 1704, as shown, has a singleinsulated conductor 1706 and it is also an end conductor, since it ispositioned nearest to the pinched region 1718 of the shielded electricalcable 1702.

First and second shielding films 1708 are disposed on opposite sides ofthe cable and include cover portions 1707. In transverse cross section,the cover portions 1707 substantially surround conductor set 1704. Anoptional adhesive layer 1710 is disposed between the pinched portions1709 of the shielding films 1708 and bonds shielding films 1708 to eachother in the pinched regions 1718 of the cable 1702 on both sides ofconductor set 1704. The optional adhesive layer 1710 may extendpartially or fully across the cover portion 1707 of the shielding films1708, e.g., from the pinched portion 1709 of the shielding film 1708 onone side of the conductor set 1704 to the pinched portion 1709 of theshielding film 1708 on the other side of the conductor set 1704. Cable1702 further includes EMI absorbing layers 1750 disposed on conductorset 1704 and shielding films 1708 on both sides of the cable.

Insulated conductor 1706 is effectively arranged as a coaxial cablewhich may be used in a single ended circuit arrangement. Shielding films1708 may include a conductive layer 1708 a and a non-conductivepolymeric layer 1708 b. In some embodiments, as illustrated by FIGS. 7 aand 7 b, the conductive layer 1708 a faces the insulated conductors.Alternatively, the orientation of the conductive layers of one or bothof shielding films 1708 may be reversed, as discussed elsewhere herein.

Shielding films 1708 include a concentric portion that is substantiallyconcentric with the end conductor 1706 of the conductor set 1704. Theshielded electrical cable 1702 includes transition regions 1736.Portions of the shielding film 1708 in the transition region 1736 of thecable 1702 are transition portions 1734 of the shielding films 1708. Insome embodiments, shielded electrical cable 1702 includes transitionregions 1736 positioned on both sides of the conductor set 1704 and insome embodiments, the transition regions 1736 may be positioned on onlyone side of conductor set 1704.

Transition regions 1736 are defined by shielding films 1708 andconductor set 1704. The transition portions 1734 of the shielding films1708 in the transition regions 1736 provide a gradual transition betweenconcentric portions 1711 and pinched portions 1709 of the shieldingfilms 1708. As opposed to a sharp transition, such as, e.g., aright-angle transition or a transition point (as opposed to a transitionportion), a gradual or smooth transition, such as, e.g., a substantiallysigmoidal transition, provides strain and stress relief for shieldingfilms 1708 in transition regions 1736 and prevents damage to shieldingfilms 1708 when shielded electrical cable 1702 is in use, e.g., whenlaterally or axially bending shielded electrical cable 1702. This damagemay include, e.g., fractures in conductive layer 1708 a and/or debondingbetween conductive layer 1708 a and non-conductive polymeric layer 1708b. In addition, a gradual transition prevents damage to shielding films1708 in manufacturing of shielded electrical cable 1702, which mayinclude, e.g., cracking or shearing of conductive layer 1708 a and/ornon-conductive polymeric layer 1708 b. Use of the disclosed transitionregions on one or both sides of one, some or all of the conductor setsin a shielded electrical ribbon cable represents a departure fromconventional cable configurations, such as, e.g., a typical coaxialcable, wherein a shield is generally continuously disposed around asingle insulated conductor, or a typical conventional twinaxial cable,in which a shield is continuously disposed around a pair of insulatedconductors.

According to one aspect of at least some of the disclosed shieldedelectrical cables, acceptable electrical properties can be achieved byreducing the electrical impact of the transition region, e.g., byreducing the size of the transition region and/or carefully controllingthe configuration of the transition region along the length of theshielded electrical cable. Reducing the size of the transition regionreduces the capacitance deviation and reduces the required space betweenmultiple conductor sets, thereby reducing the conductor set pitch and/orincreasing the electrical isolation between conductor sets. Carefulcontrol of the configuration of the transition region along the lengthof the shielded electrical cable contributes to obtaining predictableelectrical behavior and consistency, which provides for high speedtransmission lines so that electrical data can be more reliablytransmitted. Careful control of the configuration of the transitionregion along the length of the shielded electrical cable is a factor asthe size of the transition portion approaches a lower size limit.

An electrical characteristic that is often considered is thecharacteristic impedance of the transmission line. Any impedance changesalong the length of a transmission line may cause power to be reflectedback to the source instead of being transmitted to the target. Ideally,the transmission line will have no impedance variation along its length,but, depending on the intended application, variations up to 5-10% maybe acceptable. Another electrical characteristic that is oftenconsidered in twinaxial cables (differentially driven) is skew orunequal transmission speeds of two transmission lines of a pair along atleast a portion of their length. Skew produces conversion of thedifferential signal to a common mode signal that can be reflected backto the source, reduces the transmitted signal strength, createselectromagnetic radiation, and can dramatically increase the bit errorrate, in particular jitter. Ideally, a pair of transmission lines willhave no skew, but, depending on the intended application, a differentialS-parameter SCD21 or SCD12 value (representing the differential-tocommon mode conversion from one end of the transmission line to theother) of less than −25 to −30 dB up to a frequency of interest, suchas, e.g., 6 GHz, may be acceptable. Alternatively, skew can be measuredin the time domain and compared to a required specification. Shieldedelectrical cables described herein may achieve skew values of less thanabout 20 picoseconds/meter (psec/m) or less than about 10 psec/m at datatransfer speeds up to about 10 Gbps, for example.

Referring again to FIGS. 7 a-7 b, in part to help achieve acceptableelectrical properties, transition regions 1736 of shielded electricalcable 1702 may each include a cross-sectional transition area 1736 a.The transition area 1736 a is smaller than a cross-sectional area 1706 aof insulated conductor 1706. As best shown in FIG. 7 b, cross-sectionaltransition area 1736 a of transition region 1736 is defined bytransition points 1734′ and 1734″.

The transition points 1734′ occur where the shielding films deviate frombeing substantially concentric with the end insulated conductor 1706 ofthe conductor set 1704. The transition points 1734′ are the points ofinflection of the shielding films 1708 at which the curvature of theshielding films 1708 changes sign. For example, with reference to FIG. 7b, the curvature of the upper shielding film 1708 transitions fromconcave downward to concave upward at the inflection point which is theupper transition point 1734′. The curvature of the lower shielding film1708 transitions from concave upward to concave downward at the lowerinflection point which is the transition point 1734′. The othertransition points 1734″ occur where a separation between the pinchedportions 1709 of the shielding films 1708 exceeds the minimumseparation, d₁, of the pinched portions 1709, by a predetermined factor,e.g., about 1.2 to about 1.5. In addition, each transition area 1736 amay include a void area 1736 b. Void areas 1736 b on either side of theconductor set 1704 may be substantially the same. Further, adhesivelayer 1710 may have a thickness T_(ac) at the concentric portion 1711 ofthe shielding film 1708, and a thickness at the transition portion 1734of the shielding film 1708 that is greater than thickness T_(ac).Similarly, adhesive layer 1710 may have a thickness T_(ap) between thepinched portions 1709 of the shielding films 1708, and a thickness atthe transition portion 1734 of the shielding film 1708 that is greaterthan thickness T_(ap). Adhesive layer 1710 may represent at least 25% ofcross-sectional transition area 1736 a. The presence of adhesive layer1710 in transition area 1736 a, in particular at a thickness that isgreater than thickness T_(ac) or thickness T_(ap), contributes to thestrength of the cable 1702 in the transition region 1736.

Careful control of the manufacturing process and the materialcharacteristics of the various elements of shielded electrical cable1702 may reduce variations in void area 1736 b and the thickness ofconformable adhesive layer 1710 in transition region 1736, which may inturn reduce variations in the capacitance of cross-sectional transitionarea 1736 a. Shielded electrical cable 1702 may include transitionregion 1736 positioned on one or both sides of conductor set 1704 thatincludes a cross-sectional transition area 1736 a that is substantiallyequal to or smaller than a cross-sectional area 1706 a of conductor1706. Shielded electrical cable 1702 may include a transition region1736 positioned on one or both sides of conductor set 1704 that includesa cross-sectional transition area 1736 a that is substantially the samealong the length of conductor 1706. For example, cross-sectionaltransition area 1736 a may vary less than 50% over a length of 1 meter.Shielded electrical cable 1702 may include transition regions 1736positioned on both sides of conductor set 1704 that each include across-sectional transition area, wherein the sum of cross-sectionalareas 1734 a is substantially the same along the length of conductor1706. For example, the sum of cross-sectional areas 1734 a may vary lessthan 50% over a length of 1 meter. Shielded electrical cable 1702 mayinclude transition regions 1736 positioned on both sides of conductorset 1704 that each include a cross-sectional transition area 1736 a,wherein the cross-sectional transition areas 1736 a are substantiallythe same. Shielded electrical cable 1702 may include transition regions1736 positioned on both sides of conductor set 1704, wherein thetransition regions 1736 are substantially identical. Insulated conductor1706 has an insulation thickness T₁, and transition region 1736 may havea lateral length L_(t) that is less than insulation thickness T₁. Thecentral conductor of insulated conductor 1706 has a diameter D_(c), andtransition region 1736 may have a lateral length L_(t) that is less thanthe diameter D_(c). The various configurations described above mayprovide a characteristic impedance that remains within a desired range,such as, e.g., within 5-10% of a target impedance value, such as, e.g.,50 Ohms, over a given length, such as, e.g., 1 meter.

Factors that can influence the configuration of transition region 1736along the length of shielded electrical cable 1702 include themanufacturing process, the thickness of conductive layers 1708 a andnon-conductive polymeric layers 1708 b, adhesive layer 1710, and thebond strength between insulated conductor 1706 and shielding films 1708,to name a few.

In one aspect, conductor set 1704, shielding films 1708, and transitionregion 1736 are cooperatively configured in an impedance controllingrelationship. An impedance controlling relationship means that conductorset 1704, shielding films 1708, and transition region 1736 arecooperatively configured to control the characteristic impedance of theshielded electrical cable.

FIGS. 8 a-8 b illustrate, in transverse cross section, two exemplaryembodiments of a shielded electrical cable which has two insulatedconductors in a conductor set. Referring to FIG. 8 a, shieldedelectrical cable 1802 generally lies in the xy-plane and includes asingle conductor set 1804 including two individually insulatedconductors 1806 extending along a length of the cable 1802 along thex-axis. Two shielding films 1808 are disposed on opposite sides of thecable 1802 and in combination substantially surround conductor set 1804.An optional adhesive layer 1810 is disposed between pinched portions1809 of the shielding films 1808 and bonds shielding films 1808 to eachother on both sides of conductor set 1804 in the pinched regions 1818 ofthe cable 1802. Insulated conductors 1806 can be arranged generally in asingle plane, such as the xy-plane, and effectively in a twinaxial cableconfiguration. The twinaxial cable configuration can be used in adifferential pair circuit arrangement or in a single ended circuitarrangement. Shielding films 1808 may include a conductive layer 1808 aand a non-conductive polymeric layer 1808 b or may include theconductive layer 1808 a without the non-conductive polymeric layer 1808b. FIG. 8 a shows conductive layer 1808 a facing insulated conductors1806, but in alternative embodiments, one or both of the shielding filmsmay have a reversed orientation. Cable 1802 further includes EMIabsorbing layers 1850 that are disposed on conductor set 1804 andshielding films 1808 on both sides of the cable.

The cover portion 1807 of at least one of the shielding films 1808includes concentric portions 1811 that are substantially concentric withcorresponding end conductors 1806 of the conductor set 1804. In thetransition region 1836 of the cable 1802, transition portion 1834 of theshielding films 1808 are between the concentric portions 1811 and thepinched portions 1809 of the shielding films 1808. Transition portions1836 are positioned on both sides of conductor set 1804 and each suchportion includes a cross-sectional transition area 1836 a. The sum ofcross-sectional transition areas 1836 a is preferably substantially thesame along the length of conductors 1806. For example, the sum ofcross-sectional areas 1836 a may vary less than 50% over a length of 1meter.

In addition, the two cross-sectional transition areas 1836 a may besubstantially the same and/or substantially identical. Thisconfiguration of transition regions contributes to a characteristicimpedance for each conductor 1806 (single-ended) and a differentialimpedance that both remain within a desired range, such as, e.g., within5-10% of a target impedance value over a given length, such as, e.g., 1meter. In addition, this configuration of transition region 1836 mayminimize skew of the two conductors 1806 along at least a portion oftheir length.

When the cable is in an unfolded, planar configuration, each of theshielding films may be characterizable in transverse cross section by aradius of curvature that changes across a width of the cable 1802. Themaximum radius of curvature of the shielding film 1808 may occur, forexample, at the pinched portion 1809 of the cable 1802 or near thecenter point of the cover portion 1807 of the multi-conductor cable set1804 illustrated in FIG. 8 a. At these positions, the film may besubstantially flat and the radius of curvature may be substantiallyinfinite. The minimum radius of curvature of the shielding film 1808 mayoccur, for example, at the transition portion 1834 of the shielding film1808. In some embodiments, the radius of curvature of the shielding filmacross the width of the cable is at least about 50 micrometers, i.e.,the radius of curvature does not have a magnitude smaller than 50micrometers at any point along the width of the cable, between the edgesof the cable. In some embodiments, for shielding films that include atransition portion, the radius of curvature of the transition portion ofthe shielding film is similarly at least about 50 micrometers.

In an unfolded, planar configuration, shielding films 1808 that includea concentric portion and a transition portion are characterizable by aradius of curvature of the concentric portion, R₁, and/or a radius ofcurvature of the transition portion r₁, which are illustrated in FIG. 8a. In some embodiments, R₁/r₁ is in a range of 2 to 15.

Referring to FIG. 8 b, shielded electrical cable 1902 is similar in someaspects to shielded electrical cable 1802. Whereas shielded electricalcable 1802 has individually insulated conductors 1806, shieldedelectrical cable 1902 has jointly insulated conductors 1906.Nonetheless, transition regions 1936 are substantially similar totransition regions 1836 and provide the same benefits to shieldedelectrical cable 1902.

FIGS. 9 a-9 b illustrate variations in position and configuration of thetransition portions. In these exemplary embodiments, the shielding films2008, 2108 have an asymmetric configuration which changes the positionof the transition portions relative to more symmetric embodiment suchthat of FIG. 8 a. Shielded electrical cables 2002 (FIG. 9 a) and 2102(FIG. 9 b) have pinched portions 2009 of shielding films 2008, 2108 thatlie in a plane that is offset from the plane of symmetry of theinsulated conductors 2006, 2106. As a result, the transition regions2036, 2136 have a somewhat offset position and configuration relative toother depicted embodiments. However, by ensuring that the transitionregions 2036, 2136 are positioned substantially symmetrically withrespect to corresponding insulated conductors 2006, 2106 (e.g., withrespect to a vertical plane between the conductors 2006, 2106), and thatthe configuration of transition regions 2036, 2136 is carefullycontrolled along the length of shielded electrical cables 2002, 2102,shielded electrical cables 2002, 2102 can be configured to still provideacceptable electrical properties. Cable 2002 further includes EMIabsorbing layers 2050 that are disposed on conductor set 2004 andshielding films 2008 on both sides of the cable. Cable 2102 furtherincludes EMI absorbing layers 2150 that are disposed on conductor set2104 and shielding films 2108 on both sides of the cable.

FIGS. 10 a-10 c, 13 and 14 illustrate additional exemplary embodimentsof shielded electrical cables. FIGS. 11 a-11 g, 12 a-12 b and 15 a-15 fillustrate several exemplary embodiments of a pinched portion of ashielded electrical cable. FIGS. 10 a-15 f illustrate examples of apinched portion that is configured to electrically isolate a conductorset of the shielded electrical cable. The conductor set may beelectrically isolated from an adjacent conductor set (e.g., to minimizecrosstalk between adjacent conductor sets, FIGS. 10 a-10 c and 11 a-11g) or from the external environment of the shielded electrical cable(e.g., to minimize electromagnetic radiation escape from the shieldedelectrical cable and minimize electromagnetic interference from externalsources, FIGS. 14 and 15 a-15 f). In both cases, the pinched portion mayinclude various mechanical structures to change the electricalisolation. Examples include close proximity of the shielding films, highdielectric constant material between the shielding films, groundconductors that make direct or indirect electrical contact with at leastone of the shielding films, extended distance between adjacent conductorsets, physical breaks between adjacent conductor sets, intermittentcontact of the shielding films to each other directly eitherlongitudinally, reduction of spacing between the EMI absorbing layers,transversely, or both, and conductive adhesive, to name a few. In oneaspect, a pinched portion of the shielding films is defined as a portionof the shielding films that is not covering a conductor set.

FIG. 10 a shows, in cross section, a shielded electrical cable 2202 thatincludes two conductor sets 2204 a, 2204 b spaced apart across a widthof the cable 2202 along the y-axis and extending longitudinally along alength of the cable 2202 along the x-axis. Each conductor set 2204 a,2204 b includes two insulated conductors 2206 a, 2206 b. Two shieldingfilms 2208 are disposed on opposite sides of the cable 2202.Furthermore, two EMI absorbing layers 2250 are disposed on the shieldingfilms on the opposite sides of cable 2202. In transverse cross section,cover portions 2207 of the shielding films 2208 substantially surroundconductor sets 2204 a, 2204 b in cover regions 2214 of the cable 2202.For example, the cover portions 2207 of the shielding films 2208 incombination substantially surround each conductor set 2204 a, 2204 b byencompassing at least 70% of a periphery of each conductor set 2204 a,2204 b. In pinched regions 2218 of the cable 2202, on both sides of theconductor sets 2204 a, 2204 b, the shielding films 2208 include pinchedportions 2209. In shielded electrical cable 2202, the pinched portions2209 of shielding films 2208 and insulated conductors 2206 are arrangedgenerally in a single plane when the cable 2202 is in a planar and/orunfolded arrangement. Pinched portions 2209 positioned in betweenconductor sets 2204 a, 2204 b are configured to electrically isolateconductor sets 2204 a, 2204 b from each other.

When arranged in a generally planar, unfolded arrangement, asillustrated in FIG. 10 a, the high frequency electrical isolation of thefirst insulated conductor 2206 a in the conductor set 2204 relative tothe second insulated conductor 2206 b in the conductor set 2204 issubstantially less than the high frequency electrical isolation of thefirst conductor set 2204 a relative to the second conductor set 2204 b.For example, the high frequency isolation of the first insulatedconductor relative to the second conductor is a first far end crosstalkC1 at a specified frequency of 3-15 GHz and a length of 1 meter, and thehigh frequency isolation of the first conductor set relative to theadjacent conductor set is a second far end crosstalk C2 at the specifiedfrequency, and wherein C2 is at least 10 dB lower than C1.

As illustrated in the cross section of FIG. 10 a, the cable 2202 can becharacterized by a maximum separation, D, between the cover portions2207 of the shielding films 2208, a minimum separation, d₂, between thecover portions 2207 of the shielding films 2208, and a minimumseparation, d₁, between the pinched portions 2209 of the shielding films2208. In some embodiments, d₁/D is less than 0.25 or less than 0.1. Insome embodiments, d₂/D is greater than 0.33.

An optional adhesive layer 2210 may be included, as shown, between thepinched portions 2209 of the shielding films 2208. Adhesive layer 2210may be continuous or discontinuous. In some embodiments, the adhesivelayer extends fully or partially in the cover region 2214 of the cable2202, e.g., between the cover portion 2207 of the shielding films 2208and the insulated conductors 2206 a, 2206 b. The adhesive layer 2210 maybe disposed on the cover portion 2207 of the shielding film 2208 and mayextend fully or partially from the pinched portion 2209 of the shieldingfilm 2208 on one side of a conductor set 2204 a, 2204 b to the pinchedportion 2209 of the shielding film 2208 on the other side of theconductor set 2204 a, 2204 b.

The shielding films 2208 can be characterized by a radius of curvature,R, across a width of the cable 2202 and/or by a radius of curvature, r₁,of the transition portion 2212 of the shielding film and/or by a radiusof curvature, r₂, of the concentric portion 2211 of the shielding film.

In the transition region 2236, the transition portion 2212 of theshielding film 2208 can be arranged to provide a gradual transitionbetween the concentric portion 2211 of the shielding film 2208 and thepinched portion 2209 of the shielding film 2208. The transition portion2212 of the shielding film 2208 extends from a first transition point2221, which is the inflection point of the shielding film 2208 and marksthe end of the concentric portion 2211, to a second transition point2222 where the separation between the shielding films exceeds theminimum separation, d₁, of the pinched portions 2209 by a predeterminedfactor.

In some embodiments, the cable 2202 includes at least one shielding filmthat has a radius of curvature, R, across the width of the cable that isat least about 50 micrometers and/or the minimum radius of curvature,r₁, of the transition portion 2212 of the shielding film 2202 is atleast about 50 micrometers. In some embodiments, the ratio of theminimum radius of curvature of the concentric portion to the minimumradius of curvature of the transition portion, r₂/r₁ is in a range of 2to 15.

FIG. 10 b is a cross sectional view of a shielded electrical cable 2302that includes two conductor sets 2304 spaced apart from each otheracross a width of the cable 2302 along the y-axis and extendinglongitudinally along a length of the cable 2302 along the x-axis. Eachconductor set 2304 includes one insulated conductor 2306, two shieldingfilms 2308, and two EMI absorbing layers 2350 disposed on opposite sidesof the cable 2302. In transverse cross section, the cover portions 2307of the shielding films 2308 in combination substantially surround theinsulated conductor 2306 of conductor sets 2304 in a cover region 2314of the cable 2302. In pinched regions 2318 of the cable 2302, on bothsides of the conductor sets 2304, the shielding films 2308 includepinched portions 2309. In shielded electrical cable 2302, pinchedportions 2309 of shielding films 2308 and insulated conductors 2306 canbe arranged generally in a single plane when the cable 2302 is in aplanar and/or unfolded arrangement. The cover portions 2307 of theshielding films 2308 and/or the pinched portions 2309 of the cable 2302are configured to electrically isolate the conductor sets 2304 from eachother.

As illustrated in the cross section of FIG. 10 b, the cable 2302 can becharacterized by a maximum separation, D, between the cover portions2307 of the shielding films 2308 and a minimum separation, d₁, betweenthe pinched portions 2309 of the shielding films 2308. In someembodiments, d₁/D is less than 0.25, or less than 0.1.

An optional adhesive layer 2310 may be included between the pinchedportions 2309 of the shielding films 2308. Adhesive layer 2310 may becontinuous or discontinuous. In some embodiments, the adhesive layer2310 extends fully or partially in the cover region 2314 of the cable,e.g., between the cover portion 2307 of the shielding films 2308 and theinsulated conductors 2306. The adhesive layer 2310 may be disposed onthe cover portions 2307 of the shielding films 2308 and may extend fullyor partially from the pinched portions 2309 of the shielding films 2308on one side of a conductor set 2304 to the pinched portions 2309 of theshielding films 2308 on the other side of the conductor set 2304.

The shielding films 2308 can be characterized by a radius of curvature,R, across a width of the cable 2302 and/or by a minimum radius ofcurvature, r₁, in the transition portion 2312 of the shielding film 2308and/or by a minimum radius of curvature, r₂, of the concentric portion2311 of the shielding film 2308. In the transition regions 2236 of thecable 2302, transition portions 2312 of the shielding films 2302 can beconfigured to provide a gradual transition between the concentricportions 2311 of the shielding films 2308 and the pinched portions 2309of the shielding films 2308. The transition portion 2312 of theshielding film 2308 extends from a first transition point 2321, which isthe inflection point of the shielding film 2308 and marks the end of theconcentric portion 2311, to a second transition point 2322 where theseparation between the shielding films equals the minimum separation,d₁, of the pinched portions 2309 or exceeds d₁ by a predeterminedfactor.

In some embodiments, the radius of curvature, R, of the shielding filmacross the width of the cable is at least about 50 micrometers and/orthe minimum radius of curvature in the transition portion of theshielding film is at least 50 micrometers.

FIG. 10 c shows, in cross section, a shielded electrical cable 2402 thatincludes two conductor sets 2404 a, 2404 b spaced apart from each otheracross a width of the cable 2402 along the y-axis and extendinglongitudinally along a length of the cable 2402 along the x-axis. Eachconductor set 2404 a, 2404 b includes two insulated conductors 2206 a,2206 b. Two shielding films 2408 a, 2408 b and two EMI absorbing layers2450 a, 2450 b are disposed on opposite sides of the cable 2402. Intransverse cross section, cover portions 2407 of the shielding films2408 a, 2408 b, in combination, substantially surround conductor sets2404 a, 2404 b in a cover region 2414 of the cable 2402. In pinchedregions 2418 of the cable 2402 on both sides of the conductor sets 2404a, 2404 b, the upper and lower shielding films 2408 a, 2408 b includepinched portions 2409.

In shielded electrical cable 2402, pinched portions 2409 of shieldingfilms 2408 and insulated conductors 2406 a, 2406 b are arrangedgenerally in different planes when the cable 2402 is in a planar and/orunfolded arrangement. One of the shielding films 2408 b is substantiallyflat. The portion of the substantially flat shielding film 2408 b in thepinched region 2418 of the cable 2402 is referred to herein as a pinchedportion 2409, even though there is little or no out of plane deviationof the shielding film 2408 b in the pinched region 2418. When the cable2402 is in a planar or unfolded configuration, the concentric 2411,transition 2412, and pinched 2407 portions of shielding film 2408 b aresubstantially coplanar.

The cover portions 2407 and/or the pinched portions 2409 of the cable2402 between conductor sets 2404 a, 2404 b are configured toelectrically isolate the conductor sets 2404 a, 2404 b from each other.When arranged in a generally planar, unfolded arrangement, asillustrated in FIG. 10 c, the high frequency electrical isolation of thefirst insulated conductor 2406 a in the first conductor set 2404 arelative to the second insulated conductor 2406 b in the first conductorset 2404 a is substantially less than the high frequency electricalisolation of either conductor 2406 a, 2406 b of the first conductor set2404 a relative to either conductor 2406 a, 2406 b of the secondconductor set 2404 b, as previously discussed.

As illustrated in the cross section of FIG. 10 c, the cable 2402 can becharacterized by a maximum separation, D, between the cover portions2407 of the shielding films 2408 a, 2408 b, a minimum separation, d₂,between the cover portions 2407 of the shielding films 2408 a, 2408 b,and a minimum separation, d₁, between the pinched portions 2409 of theshielding films 2408 a, 2408 b. In some embodiments, d₁/D is less than0.25, or less than 0.1. In some embodiments, d₂/D is greater than 0.33.

An optional adhesive layer 2410 may be disposed between the pinchedportions 2409 of the shielding films 2408 a, 2408 b. Adhesive layer 2410may be continuous or discontinuous. In some embodiments, the adhesivelayer 2410 extends fully or partially in the cover region 2414 of thecable 2402, e.g., between the cover portions 2407 of one or more of theshielding films 2408 a, 2408 b and the insulated conductors 2406 a, 2406b. The adhesive layer 2410 may be disposed on the cover portion 2407 ofone or more shielding films 2408 a, 2408 b and may extend fully orpartially from the pinched portion 2409 of the shielding films 2408 a,2408 b on one side of a conductor set 2404 a, 2404 b to the pinchedportions 2409 of the shielding films 2408 a, 2408 b on the other side ofthe conductor set 2404 a, 2404 b.

The transition portions 2412 of the curved shielding film 2408 a providea gradual transition between the concentric portions 2411 of theshielding film 2408 a and the pinched portions 2409 of the shieldingfilm 2408 a. The transition portions 2412 of the shielding film 2408 aextends from a first transition point 2421 a, which is the inflectionpoint of the shielding film 2408 a to a second transition point 2422 awhere the separation between the shielding films is equal to the minimumseparation, d₁, of the pinched portions 2409, or exceeds d₁ by apredetermined factor. The transition portion of the substantially flatshielding film 2808 b extends from a first transition point 2421 b to asecond transition point 2422 b where the separation between theshielding films is equal to the minimum separation, d₁, of the pinchedportions 2409, or exceeds d₁ by a predetermined factor. The firsttransition point 2421 b is defined by a line perpendicular to thesubstantially flat shielding film 2408 b which intersects the firsttransition point 2421 a of the shielding film 2408 a.

Curved shielding film 2408 a can be characterized by a radius ofcurvature, R, across a width of the cable 2402 and/or by a minimumradius of curvature, r₁, of the transition portions 2412 of theshielding film 2408 a and/or by a minimum radius of curvature, r₂, ofthe concentric portions 2411 of the shielding film. In some embodiments,the cable 2402 includes at least one shielding film 2408 that has aradius of curvature across the width of the cable that is at least about50 micrometers and/or a minimum radius of curvature, r₁, of thetransition portion of the shielding film that is at least about 50micrometers. In some embodiments, the ratio r₂/r₁ of the minimum radiusof curvature, r₂, of the concentric portion of the shielding film to theminimum radius of curvature, r₁, of the transition portion of theshielding film is in a range of 2 to 15.

In FIG. 11 a, shielded electrical cable 2502 includes a pinched region2518 wherein shielding films 2508 are spaced apart by a distance.Spacing apart shielding films 2508, i.e., not having shielding films2508 make direct electrical contact continuously along their seam,increases the strength of pinched region 2518. Shielded electricalcables having relatively thin and fragile shielding films may fractureor crack during manufacturing if forced to make direct electricalcontact continuously along their seam. Spacing apart shielding films2508 may permit crosstalk between adjacent conductor sets if effectivemeans are not used to reduce the crosstalk potential. Reducing crosstalkinvolves containing the electrical and magnetic fields of one conductorset so that they to not impinge on an adjacent conductor set. In theembodiment illustrated in FIG. 11 a, an effective shield againstcrosstalk is achieved by providing a low DC resistance between shieldingfilms 2508. A low DC resistance can be achieved by orienting theshielding films 2508 in close proximity. For example, pinched portions2509 of shielding films 2508 may be spaced apart by less than about 0.13mm in at least one location of pinched region 2518. The resulting DCresistance between shielding films 2508 may be less than about 15 ohms,and the resulting crosstalk between adjacent conductor sets may be lessthan about −25 dB. In some cases, the pinched region 2518 of the cable2502 has a minimum thickness of less than about 0.13 mm.

The shielding films 2508 can be spaced apart by a separation medium. Theseparation medium may include conformable adhesive layer 2510. Forexample, the separation medium may have a dielectric constant of atleast 1.5. A high dielectric constant decreases the impedance betweenshielding films 2508, thereby increasing the electrical isolation anddecreasing the crosstalk between adjacent conductor sets. Shieldingfilms 2508 may make direct electrical contact with each other in atleast one location of pinched region 2518′. Shielding films 2508 may beforced together in selected locations so that the thickness ofconformable adhesive layer 2510 is reduced in the selected locations.Forcing the shielding film together in selected locations may beaccomplished, for example, with a patterned tool making intermittentpinch contact between shielding films 2508 in these locations. Theselocations may be patterned longitudinally or transversely. In somecases, the separation medium may be electrically conductive to enabledirect electrical contact between shielding films 2508. The cross-talkbetween adjacent conductor sets may be further reduced by including EMIabsorbing layers 2550 disposed on shielding films 2508 on both sides ofcable 2502.

In FIG. 11 b, shielded electrical cable 2602 includes a pinched region2618 including a ground conductor 2612 disposed between shielding films2608 and extending along a length of the cable 2602 along the x-axis.The ground conductor 2612 may make indirect electrical contact with bothshielding films 2608, e.g., a low but non-zero DC resistance between theshielding films 2608. In some cases, the ground conductor 2612 may makedirect or indirect electrical contact with at least one of the shieldingfilms 2608 in at least one location of pinched region 2618. The shieldedelectrical cable 2602 may include a conformable adhesive layer 2610disposed between shielding films 2608 and configured to providecontrolled separation of at least one of shielding films 2608 and groundconductor 2612. The conformable adhesive layer 2610 may have anon-uniform thickness that allows ground conductor 2612 to make director indirect electrical contact with at least one of shielding films 2608in selective locations. In some cases, the ground conductor 2612 mayinclude surface asperities or a deformable wire, such as, e.g., astranded wire, to provide the controlled electrical contact betweenground conductor 2612 and at least one of shielding films 2608. Thecross-talk between adjacent conductor sets may be further reduced byincluding EMI absorbing layers 2650 disposed on shielding films 2608 onboth sides of cable 2602.

In FIG. 11 c, shielded electrical cable 2702 includes a pinched region2718. A ground conductor 2712 disposed between shielding films 2708 andmakes direct electrical contact with both shielding films 2708.

In FIG. 11 d, shielded electrical cable 2802 includes a pinched region2818 wherein shielding films 2808 make direct electrical contact witheach other by any suitable means, such as, e.g., conductive element2844. Conductive element 2844 may include a conductive plated via orchannel, a conductive filled via or channel, or a conductive adhesive,to name a few. The cross-talk between adjacent conductor sets may befurther reduced by including EMI absorbing layers 2850 disposed onshielding films 2808 on both sides of cable 2802.

In FIG. 11 e, shielded electrical cable 2902 includes a pinched region2918 that has an opening 2936 in at least one location of the pinchedregion 2918 where opening 2936 includes openings in shielding films 2908and EMI absorbing layers 2950. In other words, pinched region 2918 isdiscontinuous. Opening 2936 may include a hole, a perforation, a slit,and any other suitable element. Opening 2936 provides at least somelevel of physical separation, which contributes to the electricalisolation performance of pinched region 2918 and increases at least thelateral flexibility of shielded electrical cable 2902. This separationmay be discontinuous along the length of pinched region 2918, and may bediscontinuous across the width of pinched region 2918.

In FIG. 11 f, shielded electrical cable 3002 includes a pinched region3018 where at least one of shielding films 3008 includes a break 3038 inat least one location of pinched region 3018. In other words, at leastone of shielding films 3008 is discontinuous. In some cases, break 3038also includes a discontinuity in at least one of the two EMI absorbinglayers 3050. Break 3038 may include a hole, a perforation, a slit, andany other suitable element. Break 3038 provides at least some level ofphysical separation, which contributes to the electrical isolationperformance of pinched region 3018 and increases at least the lateralflexibility of shielded electrical cable 3002. This separation may bediscontinuous or continuous along the length of pinched region, and maybe discontinuous across the width of the pinched portion 3018.

In FIG. 11 g, shielded electrical cable 3102 includes a pinched region3118 that is piecewise planar in a folded configuration. All otherthings being equal, a piecewise planar pinched region has a greateractual surface area than a planar pinched region having the sameprojected width. If the surface area of a pinched region is much greaterthan the spacing between the shielding films 3108, the DC resistance isdecreased which improves the electrical isolation performance of thepinched region 3118. In one embodiment, a DC resistance of less than 5to 10 Ohms results in good electrical isolation. In one embodiment,pinched portion 3118 of shielded electrical cable 3102 has an actualwidth to minimum spacing ratio of at least 5. In one embodiment, pinchedregion 3118 is pre-bent and thereby increases at least the lateralflexibility of shielded electrical cable 3102. Pinched region 3118 maybe piecewise planar in any other suitable configuration. In some cases,EMI absorbing layers 3150 are also piecewise planar in pinched region3118.

FIGS. 12 a-12 b, illustrate details pertaining to a pinched regionduring the manufacture of an exemplary shielded electrical cable.Shielded electrical cable 3202 includes two shielding films 3208 and twoEMI absorbing layers 3250 and includes a pinched region 3218 whereshielding films 3208 may be substantially parallel. Shielding films 3208include a non-conductive polymeric layer 3208 b, a conductive layer 3208a disposed on non-conductive polymeric layer 3208 b, and a stop layer3208 d disposed on the conductive layer 3208 a. A conformable adhesivelayer 3210 is disposed on stop layer 3208 d. Pinched region 3218includes a longitudinal ground conductor 3212 disposed between shieldingfilms 3208.

After the shielding films are forced together around the groundconductor, the ground conductor 3212 makes indirect electrical contactwith conductive layers 3208 a of the shielding films 3208. This indirectelectrical contact is enabled by a controlled separation of conductivelayer 3208 a and ground conductor 3212 provided by stop layer 3208 d. Insome cases, the stop layer 3208 d may be or include a non-conductivepolymeric layer. As shown in the figures, an external pressure (see FIG.12 a) is used to press conductive layers 3208 a together and forceconformable adhesive layers 3210 to conform around the ground conductor(FIG. 12 b). Because stop layer 3208 d does not conform at least underthe same processing conditions, it prevents direct electrical contactbetween the ground conductor 3212 and conductive layer 3208 a ofshielding films 3208, but achieves indirect electrical contact. Thethickness and dielectric properties of stop layer 3208 d may be selectedto achieve a low target DC resistance, i.e., electrical contact of anindirect type. In some embodiments, the characteristic DC resistancebetween the ground conductor and the shielding film may be less than 10ohms, or less than 5 ohms, for example, but greater than 0 ohms, toachieve the desired indirect electrical contact. In some cases, it isdesirable to make direct electrical contact between a given groundconductor and one or two shielding films, whereupon the DC resistancebetween such ground conductor and such shielding film(s) may besubstantially 0 ohms.

FIG. 13 shows a folded shielded cable 3302. Shielded cable 3302 includestwo shielding films 3308 disposed around spaced apart conductor sets3304. Shielded cable 3302 also includes an EMI absorbing layer 3350disposed on conductor sets 3304 and shielding film 3308 on one side ofthe cable. Shielding films 3308 are disposed on opposite sides of thecable 3302 and include pinched regions 3318 on each side of theconductor sets 3304. The pinched regions 3318 are configured to belaterally bent at an angle α of at least 30°. This lateral flexibilityof pinched regions 3318 enables shielded electrical cable 3302 to befolded in any suitable configuration, such as, e.g., a configurationthat can be used in a round cable (see, e.g., FIG. 5 g). In oneembodiment, the shielding films 3308 having relatively thin individuallayers increases the lateral flexibility of pinched regions 3318. Tomaintain the integrity of these individual layers in particular underbending conditions, it is preferred that the bonds between them remainintact. For example, pinched regions 3318 may have a minimum thicknessof less than about 0.13 mm, and a bond strength between individuallayers of at least 17.86 g/mm (1 lbs/inch) after thermal exposuresduring processing or use.

In one aspect, it is beneficial to the electrical performance of ashielded electrical cable for the pinched regions to have approximatelythe same size and shape on both sides of a conductor set. Anydimensional changes or imbalances may produce imbalances in capacitanceand inductance along the length of the parallel portion. This in turnmay cause impedance differences along the length of the pinched regionand impedance imbalances between adjacent conductor sets. At least forthese reasons, control of the spacing between the shielding films may bedesired. In some cases, the pinched portions of the shielding films inthe pinched regions of the cable on both sides of a conductor set arespaced apart within about 0.05 mm of each other.

In FIG. 14, shielded electrical cable 3402 includes two conductor sets3404, each including two insulated conductors 3406, and two generallyshielding films 3408 and two EMI absorbing layers 3450 disposed onopposite sides of the electrical cable 3402 around conductor sets 3404.Shielding films 3408 include pinched portions 3418. Pinched portions3418 are positioned at or near an edge of shielded electrical cable 3402are configured to electrically isolate conductor sets 3404 from theexternal environment. In shielded electrical cable 3402, pinchedportions 3418 of shielding films 3408 and insulated conductors 3406 arearranged generally in a single plane.

In FIG. 15 a, shielded electrical cable 3502 includes a pinched region3518 wherein pinched portions 3509 of shielding films 3508 are spacedapart. Pinched region 3518 is similar to pinched region 2518 describedabove and illustrated in FIG. 11 a. Whereas pinched region 2518 ispositioned in between conductor sets, pinched region 3518 is positionedat or near an edge of shielded electrical cable 3502.

In FIG. 15 b, shielded electrical cable 3602 includes a pinched region3618 that includes a longitudinal ground conductor 3612 disposed betweenshielding films 3608. Pinched region 3618 is similar to pinched region2618 described above and illustrated in FIG. 11 b. Whereas pinchedregion 2618 is positioned in between conductor sets, pinched region 3618is positioned at or near an edge of shielded electrical cable 3602.

In FIG. 15 c, shielded electrical cable 3702 includes a pinched region3718 including a longitudinal ground conductor 3712 disposed betweenshielding films 3708. Pinched region 3718 is similar to pinched region2718 described above and illustrated in FIG. 11 c. Whereas pinchedregion 2718 is positioned in between conductor sets, pinched region 3718is positioned at or near an edge of shielded electrical cable 3702.

In FIG. 15 d, shielded electrical cable 3802 includes a pinched region3818 wherein the pinched portions 3809 of shielding films 3808 makedirect electrical contact with each other by any suitable means, suchas, e.g., conductive element 3844. Conductive element 3844 may include aconductive plated via or channel, a conductive filled via or channel, ora conductive adhesive, to name a few. Pinched region 3818 is similar topinched region 2818 described above and illustrated in FIG. 11 d.Whereas pinched region 2818 is positioned in between conductor sets,pinched region 3818 is positioned at or near an edge of shieldedelectrical cable 3802.

In FIG. 15 e, shielded electrical cable 3902 includes a pinched region3918 that is piecewise planar in a folded configuration. Pinched region3918 is similar to pinched region 3118 described above and illustratedin FIG. 11 g. Whereas pinched region 3118 is positioned in betweenconductor sets, pinched region 3918 is positioned at or near an edge ofshielded electrical cable 3902.

In FIG. 15 f, shielded electrical cable 4002 includes a pinched region4018 that is piecewise planar in a curved configuration and positionedat or near an edge of shielded electrical cable 4002. In some cases, oneor more of the shielded cables 3502-4002 can include one or more EMIabsorbing layers disposed on the conductor sets.

A shielded electrical cable according to an aspect of the presentinvention may include at least one longitudinal ground conductor, anelectrical article extending in substantially the same direction as theground conductor, and two shielding films and two EMI absorbing layersdisposed on opposite sides of the shielded electrical cable. Intransverse cross section, the shielding films and the EMI absorbinglayers substantially surround the ground conductor and the electricalarticle. In this configuration, the shielding films, the EMI absorbinglayers, and the ground conductor are configured to electrically isolatethe electrical article. The ground conductor may extend beyond at leastone of the ends of the shielding films, e.g., for termination of theshielding films to any suitable individual contact element of anysuitable termination point, such as, e.g., a contact element on aprinted circuit board or an electrical contact of an electricalconnector. Beneficially, only a limited number of ground conductors isneeded for a cable construction, and can, along with the shieldingfilms, complete an electromagnetic enclosure of the electrical article.The electrical article may include at least one conductor that extendsalong a length of the cable, at least one conductor set that extendsalong a length of the cable including one or more insulated conductors,a flexible printed circuit, or any other suitable electrical article ofwhich electrical isolation is desired. FIGS. 16 a-16 b illustrate twoexemplary embodiments of such shielded electrical cable configuration.

In FIG. 16 a, shielded electrical cable 4102 includes two spaced apartground conductors 4112 that extend along a length of the cable 4102along the x-axis, an electrical article 4140 positioned between andextending in substantially the same direction as ground conductors 4112,and two shielding films 4108 and two EMI absorbing layers 4150 disposedon opposite sides of the cable. In transverse cross section, theshielding films 4108 and the EMI absorbing layers 4150, in combination,substantially surround ground conductors 4112 and electrical article4140.

Electrical article 4140 includes three conductor sets 4104 that arespaced apart across a width of the cable 4102 along the y-axis. Eachconductor set 4104 includes two substantially insulated conductors 4106that extend along a length of the cable. Ground conductors 4112 may makeindirect electrical contact with both shielding films 4108 resulting ina low but non-zero impedance between the ground conductors 4112 and theshielding films 4108. In some cases, ground conductors 4112 may makedirect or indirect electrical contact with at least one of the shieldingfilms 4108 in at least one location of shielding films 4108. In somecases, an adhesive layer 4110 is disposed between the shielding films4108 and bonds the shielding films 4108 to each other on both sides ofground conductors 4112 and electrical article 4140. Adhesive layer 4110can be configured to provide controlled separation of at least one ofshielding films 4108 and ground conductors 4112. In one aspect, thismeans that adhesive layer 4110 has a non-uniform thickness that allowsground conductors 4112 to make direct or indirect electrical contactwith at least one of shielding films 4108 in selective locations. Theground conductors 4112 may include surface asperities or a deformablewire, such as, e.g., a stranded wire, to provide this controlledelectrical contact between ground conductors 4112 and at least one ofshielding films 4108. The shielding films 4108 can be spaced apart by aminimum spacing in at least one location of shielding films 4108, whereground conductors 4112 have a thickness that is greater than the minimumspacing. For example, the shielding films 4108 may have a thickness ofless than about 0.025 mm.

In FIG. 16 b, shielded electrical cable 4202 includes two spaced apartground conductors 4212 that extend along a length of the cable 4202along the x-axis, an electrical article 4240 positioned between andextending in substantially the same direction as ground conductors 4212,and two shielding films 4208 and two EMI absorbing layers 4250 disposedon opposite sides of the cable 4202. In transverse cross section, theshielding films and the EMI absorbing layers, in combination,substantially surround ground conductors 4212 and electrical article4240. Shielded electrical cable 4202 is similar in some respects toshielded electrical cable 4102 described above and illustrated in FIG.16 a. Whereas in shielded electrical cable 4102, electrical article 4140includes three conductor sets 4104 each including two substantiallyparallel longitudinal insulated conductors 4106, in shielded electricalcable 4202, electrical article 4240 includes a flexible printed circuitincluding three conductor sets 4242.

In some cases, a single shielding film may provide an acceptable levelof electromagnetic interference (EMI) isolation for a given application,and may reduce the proximity effect thereby decreasing signalattenuation. FIG. 17 illustrates one example of such a shieldedelectrical cable that includes only one shielding film.

Shielded electrical cable 4302, illustrated in FIG. 17, includes twospaced apart conductor sets 4304 and a single shielding film 4308 and asingle EMI absorbing layer 4350. Each conductor set 4304 includes asingle insulated conductor 4306 that extends along a length of the cable4302 along the x-axis. Insulated conductors 4306 are arranged generallyin a single plane, such as the xy-plane, and effectively in a coaxialcable configuration that can be used in a single ended circuitarrangement. Cable 4302 includes pinched regions 4318. In the pinchedregions 4318, the shielding film 4308 includes pinched portions 4309extending from both sides of each conductor set 4304. Pinched regions4318 cooperatively define a generally planar shielding film. Theshielding film 4308 includes two cover portions 4307 each partiallycovering a conductor set 4304. Each cover portion 4307 includes aconcentric portion 4311 substantially concentric with correspondingconductor 4306. Shielding film 4308 includes a conductive layer 4308 aand a non-conductive polymeric layer 4308 b. The conductive layer 4308 afaces the insulated conductors 4306. The cable 4302 may optionallyinclude an non-conductive carrier film 4346. Carrier film 4346 includespinched portions 4346″ that extend from both sides of each conductor set4304 and opposite pinched portions 4309 of the shielding film 4308. Thecarrier film 4346 includes two cover portions 4346′ each partiallycovering a conductor set 4304 opposite cover portion 4307 of shieldingfilm 4308. Each cover portion 4346′ includes a concentric portion 4346′substantially concentric with corresponding conductor 4306. Carrier film4346 may include any suitable polymeric material, including but notlimited to polyester, polyimide, polyamide-imide,polytetrafluoroethylene, polypropylene, polyethylene, polyphenylenesulfide, polyethylene naphthalate, polycarbonate, silicone rubber,ethylene propylene diene rubber, polyurethane, acrylates, silicones,natural rubber, epoxies, and synthetic rubber adhesive. Carrier film4346 may include one or more additives and/or fillers to provideproperties suitable for the intended application. Carrier film 4346 maybe used to complete physical coverage of conductor sets 4304 and add tothe mechanical stability of shielded electrical cable 4302.

Referring to FIG. 18, shielded electrical cable 4402 is similar in somerespects to shielded electrical cable 4302 described above andillustrated in FIG. 17. Whereas shielded electrical cable 4302 includesconductor sets 4304 each including a single insulated conductor 4306,shielded electrical cable 4402 includes conductor sets 4404 that havetwo insulated conductors 4406. The insulated conductors 4406 arearranged generally in a single plane and effectively in a twinaxialcable configuration which can be used in a single ended or differentialpair circuit arrangement.

Referring to FIG. 19, shielded electrical cable 4502 is similar in somerespects to shielded electrical cable 4402 described above andillustrated in FIG. 18. Whereas shielded electrical cable 4402 hasindividually insulated conductors 4406, shielded electrical cable 4502has jointly insulated conductors 4506.

In one aspect, as can be seen in FIGS. 17-19, the shielding film isre-entrant between adjacent conductor sets. In other words, theshielding film includes a pinched portion that is disposed betweenadjacent conductor sets. This pinched portion is configured toelectrically isolate the adjacent conductor sets from each other. Thepinched portion may eliminate the need for a ground conductor to bepositioned between adjacent conductor sets, which simplifies the cableconstruction and increases the cable flexibility, among other benefits.The pinched portion may be positioned at a depth d₃ (FIG. 17) that isgreater than about one third of the diameter of the insulatedconductors. In some cases, the pinched portion may be positioned at adepth d₃ that is greater than about one half of the diameter of theinsulated conductors. Depending on the spacing between adjacentconductor sets, the transmission distance, and the signaling scheme(differential versus single-ended), this re-entrant configuration of theshielding film more than adequately electrically isolates the conductorsets from each other.

The conductor sets and shielding film may be cooperatively configured inan impedance controlling relationship. In one aspect, this means thatthe partial coverage of the conductor sets by the shielding film isaccomplished with a desired consistency in geometry along the length ofthe shielded electrical cable such as to provide an acceptable impedancevariation as suitable for the intended application. In one embodiment,this impedance variation is less than 5 Ohms and preferably less than 3Ohms along a representative cable length, such as, e.g., 1 m. In anotheraspect, if the insulated conductors are arranged effectively in atwinaxial and/or differential pair cable arrangement, this means thatthe partial coverage of the conductor sets by the shielding film isaccomplished with a desired consistency in geometry between theinsulated conductors of a pair such as to provide an acceptableimpedance variation as suitable for the intended application. In somecases, the impedance variation is less than 2 Ohms and preferably lessthan 0.5 Ohms along a representative cable length, such as, e.g., 1 m.

FIGS. 20 a-20 d illustrate various examples of partial coverage of theconductor set by the shielding film and/or the EMI absorbing layer. Theamount of coverage by the shielding film and the EMI absorbing layervaries between the embodiments. In the embodiment illustrated in FIG. 20a, the conductor set has the most coverage. In the embodimentillustrated in FIG. 20 d, the conductor set has the least coverage. Inthe embodiments illustrated in FIGS. 20 a and 20 b, more than half ofthe periphery of the conductor set is covered by the shielding film andthe EMI absorbing layer. In the embodiments illustrated in FIGS. 20 cand 20 d, less than half of the periphery of the conductor set iscovered by the shielding film and the EMI absorbing layer. A greateramount of coverage provides better electromagnetic interference (EMI)isolation and reduced signal attenuation (resulting from a reduction inthe proximity effect).

Referring to FIG. 20 a, shielded electrical cable 4602 includes aconductor set 4604 and a shielding film 4608 and an EMI absorbing layer4650. Conductor set 4604 includes two insulated conductors 4606 whichextend along a length of the cable 4602 along the x-axis. Shielding film4608 and the EMI absorbing layer 4650 include pinched portions 4609extending from both sides of conductor set 4604. Pinched portions 4609cooperatively define a generally planar shielding film and EMI absorbinglayer. Shielding film 4608 further includes a cover portion 4607partially covering conductor set 4604. Cover portion 4607 includesconcentric portions 4611 substantially concentric with a correspondingend conductor 4306 of the conductor set 4604. Shielded electrical cable4602 may also have an optional non-conductive carrier film 4646. Carrierfilm 4646 includes pinched portions 4646″ extending from both sides ofconductor set 4604 and disposed opposite pinched portions 4609 ofshielding film 4608. Carrier film 4646 further includes a cover portion4646′ partially covering conductor set 4604 opposite cover portion 4607of shielding film 4608. Cover portion 4607 of shielding film 4608 coversthe top side and the entire left and right sides of conductor set 4604.Cover portion 4646′ of carrier film 4646 covers the bottom side ofconductor set 4604, completing the substantial enclosure of conductorset 4604. In this embodiment, pinched portions 4646″ and cover portion4646′ of carrier film 4646 are substantially coplanar.

Referring to FIG. 20 b, shielded electrical cable 4702 is similar insome respects to shielded electrical cable 4602 described above andillustrated in FIG. 20 a. However, in shielded electrical cable 4702,the cover portion 4707 of shielding film 4708 and EMI absorbing layer4750 covers the top side and more than half of the left and right sidesof conductor set 4704. The cover portion 4746′ of carrier film 4746covers the bottom side and the remainder (less than half) of the leftand right sides of conductor set 4704, completing the substantialenclosure of conductor set 4704. Cover portion 4746′ of carrier film4746 includes concentric portions 4746′ substantially concentric withcorresponding conductor 4706.

Referring to FIG. 20 c, shielded electrical cable 4802 is similar insome respects to shielded electrical cable 4602 described above andillustrated in FIG. 20 a. In shielded electrical cable 4802, the coverportion 4807 of shielding film 4808 and EMI absorbing layer 4850 coversthe bottom side and less than half of the left and right sides ofconductor set 4804. Cover portion 4846′ of carrier film 4846 covers thetop side and the remainder (more than half) of the left and right sidesof conductor set 4804, completing the enclosure of conductor set 4804.

Referring to FIG. 20 d, shielded electrical cable 4902 is similar toshielded electrical cable 4602 described above and illustrated in FIG.20 a. However, in shielded electrical cable 4902, cover portion 4907 ofshielding film 4908 and EMI absorbing layer 4950 covers the bottom sideof conductor set 4904. Cover portion 4946′ of carrier film 4946 coversthe top side and the entire left and right sides of conductor set 4904,completing the substantial enclosure of conductor set 4904. In somecases, pinched portions 4909 and cover portion 4907 of shielding film4908 are substantially coplanar.

Similar to embodiments of the shielded electrical cable including twoshielding films and one or more EMI absorbing layers disposed onopposite sides of the cable around a conductor set and/or around aplurality of spaced apart conductor sets, embodiments of the shieldedelectrical cable including a single shielding film and a single EMIabsorbing layer may include at least one longitudinal ground conductor.In one aspect, this ground conductor facilitates electrical contact ofthe shielding film to any suitable individual contact element of anysuitable termination point, such as, e.g., a contact element on aprinted circuit board or an electrical contact of an electricalconnector. The ground conductor may extend beyond at least one of theends of the shielding film to facilitate this electrical contact. Theground conductor may make direct or indirect electrical contact with theshielding film in at least one location along its length, and may beplaced in suitable locations of the shielded electrical cable.

FIG. 21 illustrates a shielded electrical cable 5002 having only oneshielding film 5008 and an EMI absorbing layer 5050. Insulatedconductors 5006 are arranged in two conductor sets 5004, each havingonly one pair of insulated conductors, although conductor sets havingother numbers of insulated conductors as discussed herein are alsocontemplated. Shielded electrical cable 5002 is shown to include groundconductors 5012 in various exemplary locations but any or all of theground conductors 5012 may be omitted if desired, or additional groundconductors can be included. Ground conductors 5012 extend insubstantially the same direction as insulated conductors 5006 ofconductor sets 5004 and are positioned between shielding film 5008 andcarrier film 5046. One ground conductor 5012 is included in a pinchedportion 5009 of shielding film 5008 and EMI absorbing layer 5050 andthree ground conductors 5012 are included in a conductor set 5004. Oneof these three ground conductors 5012 is positioned between insulatedconductors 5006 and shielding film 5008 and two of these three groundconductors 5012 and insulated conductors 5006 are arranged generally ina single plane.

FIGS. 22 a-22 d are cross sectional views that illustrate variousexemplary embodiments of a shielded electrical cable according toaspects of the present invention. FIGS. 22 a-22 d illustrate variousexamples of partial coverage of the conductor set by the shielding filmand the EMI absorbing layer without the presence of a carrier film. Theamount of coverage by the shielding film and the EMI absorbing layervaries between the embodiments. In the embodiment illustrated in FIG. 22a, the conductor set has the most coverage. In the embodimentillustrated in FIG. 22 d, the conductor set has the least coverage. Inthe embodiments illustrated in FIGS. 22 a and 22 b, more than half ofthe periphery of the conductor set is covered by the shielding film andthe EMI absorbing layer. In the embodiment illustrated in FIG. 22 c,about half of the periphery of the conductor set is covered by theshielding film and the EMI absorbing layer. In the embodimentillustrated in FIG. 22 d, less than half of the periphery of theconductor set is covered by the shielding film and the EMI absorbinglayer. A greater amount of coverage provides better electromagneticinterference (EMI) isolation and reduced signal attenuation (resultingfrom a reduction in the proximity effect). Although in theseembodiments, a conductor set includes two substantially parallellongitudinal insulated conductors, in other embodiments, a conductor setmay include one or more than two substantially parallel longitudinalinsulated conductors.

Referring to FIG. 22 a, a shielded electrical cable 5102 includes aconductor set 5104 and a shielding film 5108 and an EMI absorbing layer5150. The conductor set 5104 includes two insulated conductors 5106 thatextend along a length of the cable 5102 along the x-axis. Shielding film5108 and EMI absorbing layer 5150 include pinched portions 5109extending from both sides of conductor set 5104. Pinched portions 5109cooperatively define a generally planar shielding film in the xy-plane.Shielding film 5108 further includes a cover portion 5107 partiallycovering conductor set 5104. Cover portion 5107 includes concentricportions 5111 substantially concentric with a corresponding endconductor 5106 of the conductor 5104. Cover portion 5107 of shieldingfilm 5108 covers the bottom side and the entire left and right sides ofconductor set 5104 in FIG. 22 a.

Referring to FIG. 22 b, shielded electrical cable 5202 is similar insome respects to shielded electrical cable 5102 described above andillustrated in FIG. 22 a. However, in shielded electrical cable 5202,cover portion 5207 of shielding film 5208 and EMI absorbing layer 5250covers the bottom side and more than half of the left and right sides ofconductor set 5204.

Referring to FIG. 22 c, shielded electrical cable 5302 is similar toshielded electrical cable 5102 described above and illustrated in FIG.22 a. However, in shielded electrical cable 5302, cover portion 5307 ofshielding film 5308 and EMI absorbing layer 5350 covers the bottom sideand about half of the left and right sides of conductor set 5304.

Referring to FIG. 22 d, shielded electrical cable 5402 is similar insome respects to shielded electrical cable 5102 described above andillustrated in FIG. 22 a. However, in shielded electrical cable 5402,cover portion 5411 of shielding film 5408 and EMI absorbing layer 5450covers the bottom side and less than half of the left and right sides ofconductor set 5404.

As an alternative to a carrier film, for example, shielded electricalcables according to aspects of the present invention may include anoptional non-conductive support. This support may be used to completephysical coverage of a conductor set and add to the mechanical stabilityof the shielded electrical cable. FIGS. 23 a-23 d are cross sectionalviews that illustrate various exemplary embodiments of a shieldedelectrical cable according to aspects of the present invention includinga non-conductive support. Although in these embodiments, anon-conductive support is used with a conductor set that includes twoinsulated conductors, in other embodiments, a non-conductive support maybe used with a conductor set that includes one or more than twosubstantially parallel longitudinal insulated conductors, or with aground conductor. The support may include any suitable polymericmaterial, including but not limited to polyester, polyimide,polyamide-imide, polytetrafluoroethylene, polypropylene, polyethylene,polyphenylene sulfide, polyethylene naphthalate, polycarbonate, siliconerubber, ethylene propylene diene rubber, polyurethane, acrylates,silicones, natural rubber, epoxies, and synthetic rubber adhesive. Thesupport may include one or more additives and/or fillers to provideproperties suitable for the intended application.

Referring to FIG. 23 a, shielded electrical cable 5502 is similar toshielded electrical cable 5102 described above and illustrated in FIG.22 a, but further includes a non-conductive support 5548 partiallycovering conductor set 5504 opposite cover portion 5507 of shieldingfilm 5508 and EMI absorbing layer 5550. The support 5548 can cover thetop side of conductor set 5504, to enclose insulated conductors 5506.The support 5548 includes a generally planar top surface 5548 a. Topsurface 5548 a and pinched portions 5509 of the shielding film 5508 aresubstantially coplanar.

Referring to FIG. 23 b, shielded electrical cable 5602 is similar toshielded electrical cable 5202 described above and illustrated in FIG.22 b, but further includes a non-conductive support 5648 partiallycovering conductor set 5604 opposite cover portion 5607 of shieldingfilm 5608 and EMI absorbing layer 5650. Support 5648 only partiallycovers the top side of conductor set 5604, leaving insulated conductors5606 partially exposed.

Referring to FIG. 23 c, shielded electrical cable 5702 is similar toshielded electrical cable 5302 described above and illustrated in FIG.22 c, but further includes a non-conductive support 5748 partiallycovering conductor set 5704 opposite cover portion 5707 of shieldingfilm 5708 and EMI absorbing layer 5750. Support 5748 covers essentiallythe entire top side of conductor set 5704, essentially fully enclosinginsulated conductors 5706. At least a portion of support 5748 issubstantially concentric with insulated conductors 5706. A portion ofsupport 5748 is disposed between insulated conductors 5706 and shieldingfilm 5708.

Referring to FIG. 23 d, shielded electrical cable 5802 is similar toshielded electrical cable 5402 described above and illustrated in FIG.22 d, but further includes a non-conductive support 5848 partiallycovering conductor set 5804 opposite cover portion 5807 of shieldingfilm 5808 and EMI absorbing layer 5850. Support 5848 only partiallycovers the top side of conductor set 5804, leaving insulated conductors5806 partially exposed. A portion of support 5848 is disposed betweeninsulated conductors 5806 and shielding film 5808.

In reference now to FIGS. 24 a and 24 b, respective perspective andcross sectional views shows a cable construction according to an exampleembodiment of the invention. Generally, an electrical ribbon cable 20102includes one or more conductor sets 20104. Each conductor set 20104includes two or more conductors (e.g., wires) 20106 extending fromend-to-end along the length of the cable 20102 along the x-axis. Each ofthe conductors 20106 is encompassed by a first dielectric 20108 alongthe length of the cable. The conductors 20106 are affixed to first andsecond films 20110, 20112 that extend from end-to-end of the cable 20102and are disposed on opposite sides of the cable 20102. A consistentspacing 20114 is maintained between the first dielectrics 20108 of theconductors 20106 of each conductor set 20104 along the length of thecable 20102. A second dielectric 20116 is disposed within the spacing20114. The dielectric 20116 may include an air gap/void and/or someother material.

The spacing 20114 between members of the conductor sets 20104 can bemade consistent enough such that the cable 20102 has equal or betterelectrical characteristics than a standard wrapped twinax cable, alongwith improved ease of termination and signal integrity of thetermination. The films 20110, 20112 may include shielding material suchas metallic foil and/or EMI absorbing material, and the films 20110,20112 may be conformably shaped to substantially surround the conductorsets 20104. In the illustrated example, films 20110, 20112 are pinchedtogether to form flat portions 20118 extending lengthwise along thecable 20102 outside of and/or between conductor sets 20104. In the flatportions 29118, the films 20110, 20112 substantially surround theconductor sets 20104, e.g., surround a perimeter of the conductor sets20104 except where a small layer (e.g., of insulators and/or adhesives)the films 20110, 20112 join each other. For example, cover portions ofthe shielding films may collectively encompass at least 75%, or at least80%, or at least 85%, or at least 90%, of the perimeter of any givenconductor set. While the films 20110, 20112 may be shown here (andelsewhere herein) as separate pieces of film, those of skill in the artwill appreciate that the films 20110, 20112 may alternatively be formedfrom a single sheet of film, e.g., folded around a longitudinalpath/line to encompass the conductor sets 20104.

The cable 20102 may also include additional features, such as one ormore drain wires 20120. The drain wires 20120 may be electricallycoupled to shielded films 20110, 20112 continually or at discretelocations along the length of the cable 20102. Generally the drain wire20102 provides convenient access at one or both ends of the cable forelectrically terminating (e.g., grounding) the shielding material. Thedrain wire 20120 may also be configured to provide some level of DCcoupling between the films 20110, 20112, e.g., where both films 20110,20112 include shielding material and EMI absorbing material.

Item 1 is a shielded electrical cable, comprising:

a plurality of conductor sets extending along a length of the cable andbeing spaced apart from each other along a width of the cable, eachconductor set including one or more insulated conductors;

first and second shielding films disposed on opposite first and secondsides of the cable, the first and second films including cover portionsand pinched portions arranged such that, in transverse cross section,the cover portions of the first and second films in combinationsubstantially surround each conductor set, and the pinched portions ofthe first and second films in combination form pinched portions of thecable on each side of each conductor set;

a first EMI absorbing layer disposed on the first side of the cable; and

a first adhesive layer bonding the first shielding film to the secondshielding film in the pinched portions of the cable;

wherein:

the plurality of conductor sets comprises a first conductor set thatcomprises neighboring first and second insulated conductors and hascorresponding first cover portions of the first and second shieldingfilms and corresponding first pinched portions of the first and secondshielding films forming a first pinched region of the cable on one sideof the first conductor set;

a maximum separation between the first cover portions of the first andsecond shielding films is D;

a minimum separation between the first pinched portions of the first andsecond shielding films is d₁;

d₁/D is less than 0.25;

a minimum separation between the first cover portions of the first andsecond shielding films in a region between the first and secondinsulated conductors is d₂; and

d₂/D is greater than 0.33.

Item 2 is the cable of item 1, wherein d₁/D is less than 0.1.

Item 3 is the cable of item 1, wherein the first EMI absorbing layer isdisposed between the first shielding film and the plurality of conductorsets.

Item 4 is the cable of item 1, wherein the first shielding film isdisposed between the first EMI absorbing layer and the plurality ofconductor sets.

Item 5 is the cable of item 1 further comprising a second EMI absorbinglayer disposed on the second side of the cable.

Item 6 is a shielded electrical cable, comprising:

a plurality of conductor sets extending along a length of the cable andbeing spaced apart from each other along a width of the cable, eachconductor set including one or more insulated conductors;

first and second shielding films disposed on opposite first and secondsides of the cable, the first and second films including cover portionsand pinched portions arranged such that, in transverse cross section,the cover portions of the first and second films in combinationsubstantially surround each conductor set, and the pinched portions ofthe first and second films in combination form pinched portions of thecable on each side of each conductor set;

a first EMI absorbing layer disposed on the first side of the cable; and

a first adhesive layer bonding the first shielding film to the secondshielding film in the pinched portions of the cable;

wherein:

the plurality of conductor sets comprises a first conductor set thatcomprises neighboring first and second insulated conductors and hascorresponding first cover portions of the first and second shieldingfilms and corresponding first pinched portions of the first and secondshielding films forming a first pinched cable portion on one side of thefirst conductor set;

a maximum separation between the first cover portions of the first andsecond shielding films is D;

a minimum separation between the first pinched portions of the first andsecond shielding films is d₁;

d₁/D is less than 0.25; and

a high frequency electrical isolation of the first insulated conductorrelative to the second insulated conductor is substantially less than ahigh frequency electrical isolation of the first conductor set relativeto an adjacent conductor set.

Item 7 is the cable of item 6, wherein d₁/D is less than 0.1.

Item 8 is the cable of item 6, wherein the high frequency isolation ofthe first insulated conductor relative to the second conductor is afirst far end crosstalk C1 at a specified frequency range of 3-15 GHzand a length of 1 meter, and the high frequency isolation of the firstconductor set relative to the adjacent conductor set is a second far endcrosstalk C2 at the specified frequency, and wherein C2 is at least 10dB lower than C1.

Item 9 is the cable of item 6, wherein the cover portions of the firstand second shielding films in combination substantially surround eachconductor set by encompassing at least 70% of a periphery of eachconductor set.

Item 10 is a shielded electrical cable, comprising:

a plurality of conductor sets extending along a length of the cable andbeing spaced apart from each other along a width of the cable, eachconductor set including one or more insulated conductors;

first and second shielding films including concentric portions, pinchedportions, and transition portions arranged such that, in transversecross section, the concentric portions are substantially concentric withone or more end conductors of each conductor set, the pinched portionsof the first and second shielding films in combination form pinchedportions of the cable on two sides of the conductor set, and thetransition portions provide gradual transitions between the concentricportions and the pinched portions; and

a first EMI absorbing layer disposed on the plurality of conductor sets;wherein

each shielding film comprises a conductive layer;

a first one of the transition portions is proximate a first one of theone or more end conductors and has a cross-sectional area A₁ defined asan area between the conductive layers of the first and second shieldingfilms, the concentric portions, and a first one of the pinched portionsproximate the first end conductor, wherein A₁ is less than across-sectional area of the first end conductor; and

each shielding film is characterizable in transverse cross section by aradius of curvature that changes across the width of the cable, theradius of curvature for each of the shielding films being at least 100micrometers across the width of the cable.

Item 11 is the cable of item 10, wherein the cross-sectional area A₁includes as one boundary a boundary of the first pinched portion, theboundary defined by the position along the first pinched portion atwhich a separation d between the first and second shielding films isabout 1.2 to about 1.5 times a minimum separation d₁ between the firstand second shielding films at the first pinched portion.

Item 12 is the cable of item 11, wherein the cross-sectional area A₁includes as one boundary a line segment having a first endpoint at aninflection point of the first shielding film.

Item 13 is the cable of item 11, wherein the line segment has a secondendpoint at an inflection point of the second shielding film.

Item 14 is a shielded electrical cable, comprising:

a plurality of conductor sets extending along a length of the cable andbeing spaced apart from each other along a width of the cable, eachconductor set including one or more insulated conductors;

first and second shielding films including concentric portions, pinchedportions, and transition portions arranged such that, in transversecross section, the concentric portions are substantially concentric withone or more end conductors of each conductor set, the pinched portionsof the first and second shielding films in combination form pinchedregions of the cable on two sides of the conductor set, and thetransition portions provide gradual transitions between the concentricportions and the pinched portions; and

a first EMI absorbing layer disposed on the plurality of conductor sets;wherein

one of the two shielding films includes a first one of the concentricportions, a first one of the pinched portions, and a first one of thetransition portions, the first transition portion connecting the firstconcentric portion to the first pinched portion;

the first concentric portion has a radius of curvature R₁ and thetransition portion has a radius of curvature r₁; and

R₁/r₁ is in a range from 2 to 15.

The embodiments discussed in this disclosure have been illustrated anddescribed herein for purposes of description of the preferredembodiment, it will be appreciated by those of ordinary skill in the artthat a wide variety of alternate and/or equivalent implementationscalculated to achieve the same purposes may be substituted for thespecific embodiments shown and described without departing from thescope of the present invention. Those with skill in the mechanical,electro-mechanical, and electrical arts will readily appreciate that thepresent invention may be implemented in a very wide variety ofembodiments. This application is intended to cover any adaptations orvariations of the preferred embodiments discussed herein. Therefore, itis manifestly intended that this invention be limited only by the claimsand the equivalents thereof

What is claimed is:
 1. A shielded electrical cable, comprising: aplurality of conductor sets extending along a length of the cable andbeing spaced apart from each other along a width of the cable, eachconductor set including one or more insulated conductors; an EMIabsorbing layer substantially surrounding each conductor set; and firstand second non-conductive polymeric layers disposed on opposite sides ofthe cable and including cover portions and pinched portions arrangedsuch that, in transverse cross section, the cover portions of the firstand second layers, in combination, substantially surround the pluralityof conductor sets, and the pinched portions of the first and secondlayers, in combination, form pinched portions of the cable on each sideof the plurality of conductor sets, wherein a maximum separation betweenthe cover portions of the first and second non-conductive polymericlayers is D, a minimum separation between the pinched portions of thefirst and second non-conductive polymeric layers is d₁, and d₁/D is lessthan about 0.25.
 2. The cable of claim 1 further comprising a shieldingfilm substantially surrounding each conductor set.
 3. The cable of claim1, wherein d₁/D is less than 0.1.
 4. The cable of claim 1 furthercomprising an adhesive layer bonding the first polymeric layer to thesecond polymeric layer in the pinched portions of the cable.
 5. Thecable of claim 1, wherein each polymeric layer is characterizable intransverse cross section by a radius of curvature that changes acrossthe width of the cable, the radius of curvature for each of thepolymeric layers being at least 100 micrometers across the width of thecable.
 6. A shielded electrical cable, comprising: a plurality ofconductor sets extending along a length of the cable and being spacedapart from each other along a width of the cable, each conductor setincluding one or more insulated conductors; first and second shieldingfilms disposed on opposite first and second sides of the cable, thefirst and second films including cover portions and pinched portionsarranged such that, in transverse cross section, the cover portions ofthe first and second films in combination substantially surround eachconductor set, and the pinched portions of the first and second films incombination form pinched portions of the cable on each side of eachconductor set; a first EMI absorbing layer disposed on the first side ofthe cable; a second EMI absorbing layer disposed on the second side ofthe cable; and an adhesive layer bonding the first shielding film to thesecond shielding film in the pinched portions of the cable.
 7. Theshielded electrical cable of claim 6, wherein the plurality of conductorsets comprises a first conductor set that comprises neighboring firstand second insulated conductors and has corresponding first coverportions of the first and second shielding films and corresponding firstpinched portions of the first and second shielding films forming a firstpinched cable portion on one side of the first conductor set; wherein amaximum separation between the first cover portions of the first andsecond shielding films is D; a minimum separation between the firstpinched portions of the first and second shielding films is d₁, and d₁/Dis less than 0.25.
 8. The cable of claim 6, wherein the cover portionsof the first and second shielding films in combination substantiallysurround each conductor set by encompassing at least 70% of a peripheryof each conductor set.